I’ve been following all of the posts on battery life and how to improve it, and I’ve searched the threads and can’t find anything on this…
Whenever I go into my Ram area, and look, I have a few applications that start up by default. I clear these every time, but then a few day later is happens again. It’s not always the same applications though… How can I make it stay?? How can I make it so I have to start theses up, so that they don’t start up by default.
You could try an app killer, however they usually end up costing you more battery than they are worth, because they keep stopping the same self starting apps. This makes the app killer run continuously. You could try an app like Juice Defender. I'm not sure of all of the details of that app but it is quite popular. Lastly you could root, giving you total control of your device. Battery life and control are some more popular reasons to root.
Hope this helps you some or gives you a place to begin.
First of all, Android does a great job at handling your RAM, so usually (unless an app malfunctions and takes over), you don't have to worry about those since they're not actually, well, active.
But I get your concern and there are a few ways to avoid apps from loading up. Unfortunately, as far as I know, there's not a single stop where you can change this. It's an app-by-app thing. The apps that start up at boot do so because you set them up to do so (or they set themselves up and you allowed them to by agreeing to their terms). Usually if an app accepts push notifications (messaging apps, e-mail), has interval checks for new information (weather widgets, apps), loads up information on your homescreen or lockscreen (calendar apps), or are just plain system apps (S-Stuff, dialer, OS) will always load up as soon as you turn your device on.
To stop this from happening, you can either freeze the app in the Application Manager (if you don't use the app at all and you're sure it won't make your phone go bonkers), change the app's settings to avoid any interval checks, etc. (some even have explicit 'load on boot' option), or limit their background operation by limiting the app to not use background data (in your Data Settings you can do this, also, per app).