ZOS bug with Loot History settings
 

if you never turn ON :
Autoloot
or
Autoloot Stolen Items

when you ON them first time, after this Loot history will autoswitch from OFF to ON, as soon as you will pick up any item

tested without any addons, on newly created heroes

Experienced
 

I too have noticed this when I made a new character recently. Personally it was corrected by reloading the ui after changing the setting for it to stick. Hope this helps somehow.

Please tell the ZOs developers by using /bug inside the game and describe how to rebuild it. They will see and fix it some time then.