I often use small brushes for correction masking. The slider is difficult to use at the left (small) end of the range, when attempting to create a small brush.
Exactly which brush are you referring to? Do you mean the repair/clone tool? Are you using the Mac or the Windows version of PhotoLab?
If you are on windows: Hold down “CTRL” and scroll the mouse wheel. If you’re on Mac I’m not sure if the same procedure will work(“CMD” instead of “CTRL”) but it would be worth a try.
Ha! Might have guessed. CTRL was the solution for my cropping question also. I’ll try it. Thank you.