                requesting immediate primary physical custody of the two oldest children.
                After conducting a hearing, the district court entered an order on
                November 8, 2012, awarding appellant sole legal and physical custody of
                the two oldest children and concluding that reunification efforts were no
                longer in the children's best interests. The district court transmitted that
                order to this court, and it was filed in this appeal.
                Jurisdiction to modify custody while appeal pending
                             Because it appeared that the district court lacked jurisdiction
                to modify custody while this appeal was pending, we directed appellant to
                show cause why this portion of the appeal should not be remanded under
                Huneycutt v. Huneycutt, 94 Nev. 79, 575 P.2d 585 (1978), and ultimately
                dismissed as moot. Having considered appellant's response, as well as the
                procedural posture of this case, we conclude that the district court lacked
                jurisdiction to grant appellant sole legal and physical custody of the two
                oldest children in the November 8, 2012, order.
                             During the pendency of an appeal, the district court is without
                jurisdiction to revisit issues that are before this court.   Mack-Manley v.
                Manley, 122 Nev. 849, 855, 138 P.3d 525, 529-30 (2006). This court has
                set forth a procedure for a limited remand when a party seeks to modify
                custody issues that are pending on appeal. See Huneycutt, 94 Nev. 79, 575
                P.2d 585, and Foster v. Dingwall, 126 Nev. , 228 P.3d 453 (2010).
                Appellant, who was represented by counsel at the time, elected not to
                follow that procedure and sought a custody modification from the district
                court without a limited remand. We certainly recognize that reunification
                can be challenging and that the district court may make temporary
                adjustments to custody on an emergency basis to protect the children's
                welfare. Id. at 856, 138 P.3d at 530. But here, the district court's award


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                  of sole custody to appellant was more permanent in nature, and thus, we
                  conclude that the district court lacked jurisdiction to enter that order
                  while this appeal was pending. Accordingly, the November 8, 2012, order
                  is void and ineffective to the extent that it actually changes the custody
                  arrangement, and we vacate that order. We express no opinion as to the
                  merits of that order, and the district court may reenter it once jurisdiction
                  is transferred back to that court.'
                  Custody arrangement as to youngest child
                              The district court's November 8, 2012, order did not indicate
                  any intent to alter the parties' joint custody of the youngest child.
                  Therefore, we will review this appeal as to that child. On appeal,
                  appellant contends that the district court improperly applied a higher,
                  beyond a reasonable doubt, standard, rather than the preponderance of
                  the evidence standard applicable to custody modifications, when
                  determining whether respondent had physically abused the youngest
                  child. Appellant argues that there was substantial evidence to support the
                  allegations of respondent's abuse. Appellant also contends that the
                  district court expressed bias against her at trial by making objections on

                         'In response to our order to show cause, appellant contends that this
                  appeal is not moot because the custody change was based on reunification
                  difficulties, and the district court did not reverse its finding that
                  respondent's alleged abuse was unsubstantiated. We disagree. The issue
                  before the district court was one of child custody. Once the district court
                  reenters an order granting appellant sole legal and physical custody of the
                  two oldest children, appellant is no longer aggrieved as to them, and there
                  is no reason for this court to reach the factual issue concerning abuse. If,
                  however, the district court changes its ruling on remand, appellant may
                  appeal from that determination if aggrieved. See Valley Bank of Nevada v.
                  Ginsburg, 110 Nev. 440, 874 P.2d 729 (1994).




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                behalf of respondent, who was representing himself, and reprimanding
                appellant's counsel for asking leading questions.
                            A court may modify primary physical custody when there has
                been a substantial change in circumstances affecting the child's welfare,
                and the child's best interest is served by the modification. Ellis v. Carucci,
                123 Nev. 145, 150-51, 161 P.3d 239, 242-43 (2007). Generally, in
                establishing the child's best interest, the court applies a preponderance of
                the evidence standard.    See Mack v. Ashlock,      112 Nev. 1062, 1066, 921
                P.2d 1258, 1261 (1996); but see NRS 125C.230(1) (providing that clear and
                convincing evidence of domestic violence creates a rebuttable presumption
                that custody with the perpetrator is not in the child's best interest). Child
                custody matters rest in the district court's sound discretion.      Wallace v.
                Wallace, 112 Nev. 1015, 1019, 922 P.2d 541, 543 (1996); Sims v. Sims, 109
                Nev. 1146, 1148, 865 P.2d 328, 330 (1993). The district court's factual
                determinations must be supported by substantial evidence.             Rico v.
                Rodriguez, 121 Nev. 695, 701, 120 P.3d 812, 816 (2005).
                            Here, the district court determined that the child abuse
                allegations against respondent were unsubstantiated by social services
                and that the district attorney's office declined to bring criminal charges
                against respondent. The court considered conflicting testimony from
                professional therapists and determined that appellant did not show by a
                preponderance of the evidence that respondent had abused the children or
                that it was in the youngest child's best interest to grant appellant primary
                physical custody. It is the duty of the trier of fact, not an appellate court,
                to weigh the credibility of witnesses. Castle v. Simmons, 120 Nev. 98, 103,
                86 P.3d 1042, 1046 (2004). Having reviewed the record, we conclude that
                the district court was fair and unbiased at trial and applied the correct


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                evidentiary standard. We further conclude that the district court's
                findings are supported by substantial evidence and that the district court
                did not abuse its discretion in its custody determination.     See Rico, 121
                Nev. at 701, 120 P.3d at 816; Wallace, 112 Nev. at 1019, 922 P.2d at 543.
                Accordingly, we affirm the district court's custody determination as to the
                youngest child. This is our final decision in this appeal. Any further
                appeal in this matter shall be assigned a new docket number.
                            It is so ORDERED.




                                                            Saitta




                cc: Hon. Chuck Weller, District Judge, Family Court Division
                     Samantha Arreguini
                     Jerod Arreguini
                     Washoe District Court Clerk




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