This page will be updated from time to time with answers to most frequent questions about Solid Explorer.
The short answer is: you shouldn’t care about that.
There is no proper way to exit the app, i.e. terminate its process. As a PC user you’re used to close the app when you’re done with it, but mobile operating systems are different. On the Android you don’t exit the app, you leave it. That’s why it doesn’t matter if you hit the home or back button. Well, actually it does, because hitting the home button will save the app state, so it’s even better. Anyway, in both cases the app will be moved to background an will sit there until you open it again or your device will run out of free RAM. In the second case, Android’s memory management will kill the process to make room for a new app. If you really want to release resources eaten by the app, remove it from recents. That will do the job.