Presuming you have assigned a Quick Key to a Favorites List, to toggle it on or off, simply press the number followed by the E/yes button.
For example Favorites List "A" has a quick key of 1. To toggle it on or off it is 1 Eyes.
Also, just to be sure, FL quick keys cannot be "shared'. That means FLQK 1 cannot apply to Favorites List "A" and "B" as a rule.
"On" and "Off" have replaced the terms "Enabled" and "Disabled" (just like "groups" are now "departments").
Lastly, if you are interested, you can change the default status of Favorites Lists Quick Keys in Sentinel. Open the profile editor and go to the Quick Keys Status tab and you'll see checkboxes.
A checked box means he FLQK is on and the FL will be scanned (presuming range and location parameters are met). You can turn them off by the FF Eyes sequence.
An unchecked box means the FLQK is off and the FL will not be scanned, unless you manually turn it on.