If you start a career mode starting in f2 and choose no practice you will not be able to change any setting of every session (distance in the race or type of qualifying) also if you do qualy, 3 laps sprint and 5 laps feature, in some races you will start the race with a compound different compared to the ia
Top right corner - you need to select 'expert'. I think it is set to 'rookie' by default and you can't really change much.
For the difficulty yes, after quali you can change the difficulty if you close the game but for the distance you can't do much
Haven't got this year's game yet but I remember from previous installments that once you set up a season you can't change it until it ends, that includes sessions and their length.
