PS4 multiple accounts, games still just for me?

Hey everyone - the following problem: playing on a PS4 with two accounts - now I buy a game, download it and it is playable for both accounts. That's exactly what I want to avoid! How can I make this really only available to me? And can I best secure my account somehow with a code? So that really nobody can access it?
That's because - with a buddy from the flat share we share the PS4 - then I got FIFA20 - usually we always share the price here too - but the sack said he never played it. Well, it wouldn't be a thing either - but now he's the one who plays most FIFA (and kills me at FIFA…).
Request for answers - if I lose against him next week on Friday I will lose an entire box!

Best wishes

It doesn't matter, play with him, he's your friend.

Share it and you're done

Change your password or go to support and say that I no longer want it to be in my account and should put it out there and be good