Hi, I've been playing in brush settings all morning and I just held down a few keys (Ctrl+Z I thought) but must have held down something else and now my brush settings control panel is all greyed out and I can't use it.
You did really well providing the screen shot, but it would be more useful if you'd shown the entire workspace. If you can do that I'm sure we can sort it out. Leave it at full res, and show layers panel, an history panel at least. Have the brush tool selected.
I agree with what @Trevor.Dennis said, but just in case, (and to reiterate what Trevor said) make sure you have the brush tool selected when you go into the Brush Settings Panel. Otherwise, yes - everything will be greyed out as you see here. If you hit CTRL+Z, it might be you went back to where you were before you had selected a brush in the first place.
Apple Studio (M1 Max), 1 TB SSD, 32 GB RAM, Monterey 12.6; Wacom Cintiq 24 Pro
Heh, so I went to look this up, and yes! Have the Brush tool selected. The bad UX here, though, for me came from when I was painting with the clone stamp tool. The brush size in the Paint Window is clickable and it sends you straight to the Brushes Window, BUT, because you're not on the Brush tool the selections are all grayed out and unlickable.
Maybe I'm crazy, but I could SWEAR that in the past whenever I was on the clone stamp (or other similar painting tools) that when I clicked the brush size in those tools and it sent me to the Brushes palette that I was able to then choose the brush sizes without having to be specifically on the Brush tool. Am I just gaslighting myself? 😄