I used to steal memes from ifunny and post them on instagram
Did you post them for a reason?
I used to post them for money
If you wanted to make money you should have created your own memes. It's not right to steal them from somewhere and say they're yours.
Can I post famous quotes instead?
I think that is fine since quotes are opening for most people to use even if it's financial but you should always look into the laws yourself just in case.