How do I restore it?

[opqriu]

How do I restore it?
I'm new to Thunderbird and testing various things.
Thank you for providing the security options for Thunderbird;
I will use them well.

However, is there a way to revert to the original settings just in case?
I've deleted the user.js file, But this is no change

[opqriu]

oh backup...

[HorlogeSkynet]

Hello @opqriu, and thanks for your message.

You can read here how FF/TB parses, saves and interprets preferences. TL; DR : it's not because you restore a previous version of the user.js previously overridden preferences will reset to their default values (as they'll be enforced in saved prefs.js).

Bye 👋