I have read over many q and A's regarding the 'force stop' option for most apps. All explain what it's function is, but aren't too clear on when it is really necessary to go thru my list of apps and force stop them (EVEN ONES THAT ARE NOT CURRENTLY IN THE LIST OF RUNNING APPS?!?!?) That was and still is a bit hard for me to understand also. If my phone says the apps are not currently running what I'd it that I'm forcing to stop? And will it effect the function or start up of the app when I need to use it?
The answer is easy: Under normal circumstances you never need to "force stop" any app. Android automatically handles which app should be stopped in case the system is running out of free RAM.
Anyway even if you force an app to stop it usually should be able to start again at any time. Note that "starting an app" may even happen without user interaction based on certain events like change of battery level, a new Wifi was found, or simply because another app has triggered the app to run in background.