Apk says " app conflicts with an existing package" do I have to backup my save and uninstall old, install new?
Yes, copy your saves to another folder. Delete the old version of the game, then install a new one and copy back your saves.
How do I do that on phone? I can't find the location of the save file...
The files are always in the same location. However, different Androids give different levels of access to system files, and it is possible that on your phone, these files are hidden or operations with them are forbidden.
