Can you change this when in the game?

Can you "Enable Attribute Masking" or whatever's its called to show all attributes for player at smaller teams etc in the middle of a game without starting a new one.

Is it changeable at all or is it in preferences or in another menu?

Thanks in advance

Attribute masking hides attributes. To turn it on would mean all attributes other than your players and ones of players you have scouted would be invisible. If a player only has half his stats then you need to scout them to get the full picture/remove the "fog of war".

I think this has to be changed before you start up a new save though.

I want to see the attributes of all players which currently I can't.

Yeah, you have to start a new game.