Firefox vs Chrome: how to open new tabs in foreground or background with same meta keys?

The Request

How can I make the same meta keys between Firefox and Chrome do the same thing?

In my macOS, currently in my environment (<click> = "mouse left click on weblink"), the following "open new weblink in new tab" keyboard behavior is inconsistent between Firefox and Chrome.

Chrome

open new-web-page tab in foreground: cmd-shift-<click>
open new-web-page tab in background: cmd-<click>

Firefox

open new-web-page tab in foreground: cmd-<click>
open new-web-page tab in background: cmd-shift-<click>

It matters less which keyboard-shorcut-plus-click does which thing (although I'd prefer the cmd-<click> opens in _background); I at least want the behavior to be consistent between these 2 web-browsing apps.

My current versions

macos: 10.14.6
firefox: 76.0.1 (64-bit)
chrome: Version 81.0.4044.92 (Official Build) (64-bit)

Failed (thus far) solutions

I've thus far been unable to get the following solutions to help/work:

https://github.com/mikecrittenden/shortkeys/wiki/How-To-Use-Shortkeys
https://superuser.com/a/1260437/98033

Solution 1:

Employing the following Firefox preferences settings achieved what I wanted. In particular: the annotation highlights the setting I unchecked that made things work on my system.

macOS Firefox preferences