In any case, in order for anyone to investigate, you'd need to attach the specific score you are having trouble with and give precise steps to reproduce the problem. Either here if your issue is with the MsueScore notation software, or over on the appropriate group on musescore.com if your issue is with that website or its mobile apps.
Comments
By 'app' do you mean the mobile app for iOS or Android? If so: these are not being dealt with here on musescore.org
See https://musescore.org/en/faq#faq-20657
In any case, in order for anyone to investigate, you'd need to attach the specific score you are having trouble with and give precise steps to reproduce the problem. Either here if your issue is with the MsueScore notation software, or over on the appropriate group on musescore.com if your issue is with that website or its mobile apps.