Can't Change Brush Size Hotkey to Alt+RightClick+Drag

you can make a request of adobe.  

to report bugs or ideas or wishes to adobe: for applicable apps, use https://helpx.adobe.com/ie/x-productkb/global/how-to-user-voice.html

for createive cloud assets:

bugs, https://community.adobe.com/t5/adobe-collaboration-experiences/ct-p/ct-adobe-collaboration-experienc...

requests, https://community.adobe.com/t5/adobe-collaboration-experiences/ct-p/ct-adobe-collaboration-experienc...

for others, use https://www.adobe.com/products/wishform.html

if neither show a place to report the issue, just leave it here. that's the best you can do.