Hi gd4, please ignore the spam message with a phone number -- that's not official and we don't know what they will do to your system if you engage.

Hi gd4, there is no way to modify built-in keyboard shortcuts, but some extensions may be able to associate a different keyboard shortcut with the same function. These are two general purpose ones I've looked at in the past, but I don't use them myself so I don't know if moving tabs is in their repertoire.

• https://addons.mozilla.org/firefox/addon/saka-key/
• https://addons.mozilla.org/firefox/addon/shortkeys/

You also could search the Add-ons site for something purpose-built that doesn't require as many permissions.

By the way, on your keyboard, what keys are available to use that you would prefer to use?

Generally speaking, extensions shortcuts need to contain either Ctrl or Alt, but because many Ctrl combinations are already used, even adding Shift, it can be a little tricky finding an available shortcut. This article describes the valid combinations:

https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/manifest.json/commands#Shortcut_values

I'd love to use a keyboard shortcut using left and right arrows; left and right angled brackets would work too. Ctrl, alt and fn are available modifiers. I appreciate your quick replies, @jscher2000

I posted an add-on for this but it is still in the review queue. Probably will be available in the morning:

https://addons.mozilla.org/firefox/addon/hotkeys-for-tabs-left-right/

Thank you jscher2000! Works great!