Okay so what happens to your apps when you restore your iphone?

[Foolishcaption916]

I want to restore my iphone because I'm having some problems with it. However, I am concerned with losing the activity I've made on my apps. I know I can back up everything on itunes, my computer, the cloud etc....but the only thing I'm really worried about is losing my info on instagram, and apps like that. So to get to my point, if i restore my phone will I lose everything I've ever done on my apps, even if I back up my phone to everything possible, or do you have to start over completely from scratch(like creating accounts, usernames, passwords, etc...) Hope that makes sense, thanks.