Is there anyway for one person to be in control of everything? I'm letting my little brother game share with me. I doubt anything would happen with my account and I already told him it can only be used for him to download stuff through my download history. Just don't want his brothers (not related to them) messing with anything or his friends or anything. I doubt they would though. Just trying to be safe.

So whats the Q ? if you're talking about control of the content, You can set an age limit in the parental settings.

how? 

No I mean can one person be in primary control of everything?

If you give him your account you can't control anything.

You can't control other consoles that sign in?

No, you have no control at all.

My advice is to set a password, tell him about it, then change it as soon as he's done using it. That way it's only being used when you want it to be used.

You can go into your account settings and require a password at checkout on the PS Store, if that is what you are concerned about.