I would love to change back from higher T-classes. I think you have most fun in T1 and T2 right now, plus things get to expensive in higher T-classes. Of course you would have to find a mode in which the use of higher ship classes would be disabled (play T2, use only ships T1 or T2). So thats my opinion, would be glad to see changes on this in the game in the future, thumbs up for a otherwise good game!
Someone forced you to play T3+?
I think (s)he wants to play purely T2 matches without any T3 ships sneaking into them (which seems to happen a lot, far as I’ve seen - plenty of T3 fighters, inties and frigates worming into T2 matches).
But, er, yes, in case an fyi is needed - if your hangar has T2 ships (which you can reassign at will, just click on any ship you own and it will be placed in the active hangar slot) and No T3/4 in the active hangar bays, then you will get into a T2 match.
So in a sense, you already can ‘set’ your T-mode. All hangar bays with T1 ships? T1 mode. T2 ships? T2 mode. Have a T3 ship active in hangar? T3 mode…