hi there :) to be fair and precise:
- You clicked the feature. (It doesn't runs for users who didn't click it). The feature was just newly written on many users' request and by a new volunteer.
- We should also add an 'off' option '(=3-4)' above (until then you can also reinstall and start over.)
- 4 is the default on modern or large screens (unless you zoom in.)
- The option 3 was added before your review but it takes time for Mozilla to accept changes.
Firefox reviews are not intended for specific bug reports, but meant to review the whole product. (See also the answer above)
Thanks!