It helps if one provides screenshot of the settings they are referring to so other reading can see what is going on here.

Hi

This support article should help:

https://support.mozilla.org/en-US/kb/about-config-editor-firefox

I strongly recommend not altering preferences in about:config or trying to adjust any that are locked.

Here's an example:

The setting toolkit.telemetry.enabled cannot be unlocked in official builds.

On Firefox Desktop starting with 58 toolkit.telemetry.enabled is locked to "true" on beta, aurora, and nightly channels (as well as unofficial builds with the 'default' channel). It is locked to "false" in all other cases. This, rather unstraighforwardly, does not mean Telemetry is enabled. This means that, if telemetry is enabled, we collect somewhat more information.

https://bugzilla.mozilla.org/show_bug.cgi?id=1422689#c1

This controls a diminishing number of things and is intended to be deprecated, and then removed.

https://firefox-source-docs.mozilla.org/toolkit/components/telemetry/internals/preferences.html

Thanks for the clarification on that particular preference

See also:

• https://searchfox.org/mozilla-central/source/toolkit/components/telemetry/docs/internals/preferences.rst