On ElCapitan with the new Safari 11 and Cookie 5.6 (MAS) it seems like when Cookie runs that it resets the defualt Auto-Play pref for 'When visiting other websites' to 'Stop Media with Sound' even though I have it to 'Never Auto-Play.'
I was using Cookie 5.5.8 for a day or so with Safari 11 and this didn't notice this behavior-seems like it started with Cookie 5.6
So, we have to choose between history clearing and keeping the Website prefs?
Some of the site prefs do survive when Cookie runs. Like the Zoom levels are are not affected from what I can tell.
And as I mentioned, I'm pretty sure Cookie 5.5.8 in Safari 11 on 10.11.6 didn't interfere with the Auto-Play setting.
There is a work around that allows you to keep the Safari 11 website auto-play preferences while deleting preferences, but it isn't convenient. In your mac's user library go into the Safari folder. There are some files with the name PerSitePreferences.db. If you right-click on each of these files and click "Get Info" in the pop-up menu you will get the info pop-up menu for that file. If you check the "Locked" setting those files aren't erased by Cookie 5.6 or Safaris' built-in "Clear History" selection. Also, any changes that you make to the preferences in Safari while these are locked will not be saved, they will have to be unchecked again. See attachments.
@bog thanks for the excellent workaround.
I configured the Website prefs how I want then and then I locked those PerSitePreferences.db's as you suggested and the settings are holding even when Cookie 5.6 runs.
obviously, this is somewhat less than ideal since new site prefs won't be remembered, but it is working for now.
Hopefully Russell can integrate these Site Prefs into Cookie.
Ive just posted the new Beta: