Thumbnail auto deleted

Hi, I need a solution for auto deletion of my picture/video thumbnail. I'm a photographer I work with photos everyday, having randomly deletion of my thumbnail of my vast collection of my picture is indeed very annoying. I have to sit to several minute to have those thumbnail build up again. I do not tick/delete it during disk clean up. I have found previous thread discussing this, however so solution was provided. https://community.norton.com/forums/thumbnails-deleted
 

I also followed the instruction from Microsoft to remove permission from my system from auto delete it (but not user, only system permission was disallowed). However I still face the same issue. I suspect the main culprit is my Norton auto delete it when doing maintenance. However I cant find option to turn off deletion of my thumbnail.

OS: Win8.1
Product: Latest Norton 360 Multi Device

Second, problem I'm having is the need of enter password to open vault in the Identity Safe. Is there possible to turn it off. This PC user is only me, so there no need of entering the password everytime.

Please advice, thank you..