Falling back is pretty simple...
1. Open the CC Desktop App
2. Click the Apps tab
3. Click the small triangle next to DW's Open/Install/Update icon
4. Choose Other Versions from the menu that comes up
5. Pick the one you want (I use CC2015 still personally)
From there on out, any time you install a newer version, make sure to click the Advanced Options link in the bottom of the installer dialogue. That allows you to turn off the Remove Older Versions option so you can keep your older, functional version while checking for hiccups in the latest.
You can actually have all of the versions from the CC App installed on the same machines at the same time, under a single subscription, they just won't run concurrently.