To zoom in on Firefox on my PC, I hold Ctrl and move the mouse wheel up. When I try to do this on my MacBook Pro, it zooms in everything, not just what's inside Firefox.
How can I use the zoom in Firefox on a MacBook Pro?
You can use your 2 finger for zooming Firefox inside.
Or use cmd + + for zooming in.
And cmd + - for zooming out.
Moving the mouse wheel up and down while holding both