I am updating an old mod for new release, I have placed several strong boxes through out tamriel with items in them. However the items are labeled as stolen when i go in world and check them. In my container info in CK, I changed the Owner NPC to player. So obviously that didn't do what I hoped. How can I fix this so the strong boxes are not "Stolen" to the player.

When you changed owner to player did you try checking your plugin by using coc default player? If you use a savegame to check, it will likely remember the previous data stored.

COC Default Player ??? I did try using a new game after making the changes, and the strong boxes are still considered Stolen.

Is the cell you are working in flagged as player owned?

The area's are each temple dedicated to one of the divines. I had a feeling that the area might be an issue with it.

try setting the strongbox to no ownership?

Nope.. that didn't work

don't change the owner on the container, change it in the refs' owner tabs.

if your containers are editor placed, respawning with no unique items etc anyway, and if they have no scripts,

you could also just replace them with copies to 100% exclude save game issues, since these will be new refs for which no data is in any save

(or change their form id's in tes5edit, does the same).

don't do that if you placed them at runtime though (like placed by a script or an alias etc), they'd remain in the game then

(editor placed ones will cease to exist when they're not in the esp anymore)