There are changes I regret making in returner. I can't specifically reset those settings back to default without resetting everything. I don't even remember every change I made to go back and do them all again.

Export your current settings in Retuner
Rename the Scripterror XML file to 2023-05-26-Retuner.xml

Method 1
Open it with a text editor
If you reset Retuner to default you can see here what you had changed before to repeat some of them,

You can see the path in each option in the xml ...name first tag.

Method 2
Or you delete all parts in this exported XML you don't want anymore and make a Retuner tuning, get the tuning file from retuner downloads page.

1. place this tuning package in your mods folder
2. open it with nraas Packer
3. right click the XML file -> import
and choose your renamed Retuner XML
4. save
5. delete all cache files in your Sims 3 folder
Now
Open a new fresh instance of a world.
place a dummy family, place on a lot, play and let the game run some sim minutes
-> in game go to city hall and use Overwatch immediate -> Export settings, choose only Retuner and name it
2023-05_Retuner-final
(this is saved in your library)

Quit game.
Delete or move the Retuner tuning package out of the mods folder.
Delete Cache files
Start your normal save and import via Overwatch the Retuner save
Save as new and quit game
Delete Cache files
start it again and done.

when deleting parts make sure to delete all parts in the relevant option, including the Begin/Close tag like
<ITUN>
xx
</ITUN>
or
<Social>
xx
</Social>
or
<XML>
xx
</XML>

You should always export settings via Retuner if you make changes (always rename the scriterror).

1. you can then compare the current with your previous using winmerge
or Notepad++ and the plugin compare
2. This way you easily see what you have changed inbetween and it is easier to revert only a few options in game, if they are not good
3. to revert to a previous state, well method 2 again or manually revert ingame

Of course you can also use Overwatch to export settings everytime you make changes, these are saved in the library.
when you have done an export via Overwatch:
- switch to the library folder, sort descending date and rename the newest the same 2023-05_Retuner or the complete date if you do a lot exports.
then you can easily sotrt out and maybe delete older stuff you are sure you don't need anymore.

the default values you can find in here:
FullEATuning_P163 DEFAULTS

• Download

If you like to use the tuning package to have all your settings in all games
- be aware that then if you export xml via Retuner only your "new" changes are exported, not all.

So you would have to add these new parts manually in the right section of your tuning xml.
Either by using the complete Final xml you have previously imported via Packer (edit with texteditor) to the tuning
and import again via Packer

OR copy paste the new parts in this (right sections) in Packer right-click the xml -> edit.

Personally I prefer the import via Overwatch.