I'm having troubel making subs in ultimate team. I can't make subs.

I'm having trouble making subs in ultimate team. I can't make subs. If I go to team management I can't get out either. I tried my friend's account on my PC and I was able to make subs with his account. so i think the problem is with my account. I redownloaded the game and the EA app but it didn't work. can anyone help. i play on pc.