How to make google chrome/internet explorer ask for a password before downloading anything?

My brother downloads alot of space consuming things on my laptop without asking (ugly minecraft mods and **** I wanna slap that b*tch).so I need something thats going to keep me tension free.

Computers have the ability to have separate accounts. You should have an admin acct, a acct for your bro, and one for you.

Each of you can have different programs only accessible by you. If he corrupts his acct by downloading a virus - you just go into the admin acct and delete his acct.