Changing the Slow-mo music
Starting with version 1.4.0 you can change the music that is used in your slow-mo videos. To see what version of the app you have, go to the App Store, search 'Booth.Events', check that you can see at least version 1.4.0 and no update is available.
First you need to save your music file onto your iPad. You can use AirDrop, or Dropbox, or download it with Safari, or email it to yourself. Then, save it to your iPad so that when you open the Files app, you can see it there.
Next, open up the Booth.Events app and navigate to the home screen and touch the "Audio tracks" button:
Touch the "Add Audio Track" button:
When the iOS File Chooser pops up, choose the file you saved on your iPad at the beginning.
Your newly added audio file will be automatically selected: it will show a blue checkmark on the right of the row.
You can add and select multiple audio files. When you do this, every time a video is made, a random audio file will be chosen from those that are selected.