Is there anywhere I can access/reinstall the previous version app, which worked on 7.1.2? Can't find it in iTunes or App Store, only the new version.
Acrobat app auto updated and now won't work. Any help would be appreciated.
Unfortunately, Apple (not Adobe) provides no options to downgrade iOS nor any iOS apps (from the App Store).
For example, once you upgrade your operating system on your iPad/iPhone from iOS 7 to iOS 8, you cannot go back to iOS 7 (unless your iPad/iPhone is jailbroken).
Similarly, the Apple App Store detects the iOS running on your iPad/iPhone and selects the latest compatible version of an app. The App Store does not offer the user interface (dialog or list) with multiple versions of the app for users (like yourself) to choose from.
If you have the full backup of your iPad/iPhone before installing the latest version of Acrobat Reader for iOS, you could restore it and turn off the app auto update.
Would you describe the problems that you've encountered with the latest version of Acrobat Reader for iOS? Please be very specific. We can try to address them if we understand what you don't like about it.