When quitting Picard, settings are not saved. Window size and location, login details, file naming strings -everything resets to defaults. I have to enter/change all of this on each launch. Oddly, this happens on my account but if I create a fresh account it doesn't happen there.

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Updated: I've figured out why this was happening (and probably why I also had the problem mentioned here: https://tickets.metabrainz.org/browse/PICARD-1212) 

This is due to a permissions error on the ~/.config folder. For some reason the owner was system, not myself. Once changed, this resolved. For whatever reason (system upgrade from 10.12-10.13??) the permissions were changed. .config isn't a typical location for OS X .app configs, so only Picard was experiencing problems. This is also why Sambhav was unable to produce the error on PICARD-1212. I created a fresh user account and didn't experience the bug, I then ran another python app and it too experienced a loss of settings - this led me to the .config folder. It's also why I couldn't find a settings file, because Picard had no permission to create one! 

For those affected, this in terminal should sort:

sudo chown -R [yourusername] ~/.config 

Thanks

PS. This platform sucks. I've just edited several times on 2 different posts to try and mention, and it's showing no visible signs of doing so.

Additional:

You may also need to do:

sudo diskutil resetUserPermissions / `id -u`

And:

sudo chmod -R 744 ~/.config

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Notes: Changed type to story, as not a bug.