Difficulty settings gone after starting career?

I remember seeing one of these tiles called "Difficulty", and I'm pretty sure it was all the way to the left on the second row. In fact, I kind of remember seeing it a few weeks ago. I don't play the game every day so I'm not totally sure.

But, is that tile supposed to be there after you start a custom career? The main problem I have right now is that I'm about a month or more into this career, and when I started it, I set the difficulty to 5 I think. As I became a little better with time, that level doesn't work for me anymore, because I win every single race rather easily. Sometimes I may finish with Verstappen and Russell right behind me, but I still win, and for most of the race, it feels like I'm driving in practice mode because I don't have cars behind for most of the race. 

I'm not saying I'm a superb driver, I'm just better than when I started, so ideally I would like to raise that level to 10 and see what happens, and maybe keep racing it as I progress in my career. Is that possible, or the whole career stays at the difficulty level you started it with?