In some cases, you may run into issues with the beta version. If you do, please let us know what the problem is by reporting an issue.
In TestFlight, select Bouncie, then click 'Previous Builds.' Here you can select and install an earlier beta version of Bouncie.
Unfortunately, there is no way to temporarily install another beta version of the app. If the app is not usable to you, you can temporarily leave the beta program. Of course, we will do all we can to fix any critical issues as soon as possible.