How do I Stop my assistant manager offering contracts to youngsters?

Where is that screen - like manager options I think it was called, where you can tell your ass man to take control of teamtalks and the contracts etc.

Cant find it anywhere.

Assuming the default skin -

Along the top bar, to the right of Continue, find the Manager drop-down. Highlight your team name, e.g., York. Bottom entry of the sub-menu is Team Settings. There should be three entries within, one each for your First Team, your Reserves, and your Youth side. Uncheck them all.