Changing the size of the brush / blob brush tool (shortcut) doesn't work!

[Stefan33241126yuee]

I try to change the size with the square brackets.... [] but when I click option in the brush/blob brush tool then the smooth tool appears and I can do nothing except using the smooth tool. I need to click on option and then on 5/6 to make square brackets. But when I click on option then the smooth tool appears and thats the problem. How can I fix this?

[Ton Frederiks]

You cannot change the brush size in the brush options, you can change it by choosing another brush or by using the bracket keys. What do your keyboard shortcuts show? What do you use as input device?