Originally Posted by ectoplasm
Agreed. I think there was an issue in an earlier version of Android that was resolved, but the urban legend continues.
If you really need to stop an app, just go to settings -> applications -> the app name -> force stop button
Keep in mind that some apps running in the background aren't suspended and will drain your battery. Mantano was running in the background because it was searching the entire Fire for epubs and pdfs. Now leaving that running will drain the battery not sure how much but it's possible it's got stuck in memory due to compatibility issues.
So we now know how to fix it to close down when exiting.