How to Zoom in and out with one finger (in Firefox)

[Edwardo]

Some may find this useful

Customizable shortcuts
https://addons.mozilla.org/en-US/firefo ... src=search

e.g. I need to zoom in on almost every page several magnitudes so this works OK.

Center '5' key number pad to zoom in & 'Insert" to zoom out, see how that works out, or any keys of your choice.

Install, restart FF, go to Edit > Preferences > Shortcuts to customize.