You may be confusing the windows and mac shortcuts. To change brush size use:
Windows, Alt+right click
Mac, Control+Option click
Drag right/left to change size
Drag up/down to change hardness
before it use to be :
ctrl + alt + click
but now i did not work anymore with CC 2017.
ctrl + cmd + click (did not work too...).
what is the new shortkey please ?
and another change, before we can ajust the size of the image with "swift + alt" to change size from the center and keep the proportion, but now when you use "alt" it did not keep the proportion anymore.
how can we resolve this please ?
With the Brush tool selected
On a Mac:
Control + Option then drag left/right in order to decrease/ increase brush size.
Control + Option then drag up/down to decrease/ increase brush hardness.
Ctrl + Mouse Click to see this:
Alt + Right Mouse -drag left right to decrease/ increase brush size and up/down decrease/ increase brush hardness.
Regarding resizing the image, did you press (mac) Command + T (win) Ctrl + T first?