Avast Sandbox question

I have checked , that if i start firefox sandboxed , that all my extensions and everything is not virtualizised.

but i am still protected right , if i visit bad sites ,or if i download a bad extension ?

and i have unchecked , that avast sandbox saves your things if u close the browser , so if i close my browser now , everthing inside it gets flushed right ?

I am no expert on Firefox and Avast Sandbox.

However here are couple of things that I can point out that I think are correct.

If you Sandbox Firefox without any Exclusions then when you close Firefox any Malware that may have gotten into the Sandbox will be deleted or quarantined when you close Firefox. In any case if you use Firefox in the Sandbox mode without any Exclusions you should be protected from Malware getting onto your system via surfing with Firefox. Of course whatever you do in Firefox like adding or updating Addons will be lost if you subsequently run Firefox in the Normal mode.

If you exclude certain items like Bookmarks under the Sandbox Expert Settings then those Bookmarks along with any Malware that they carry will remain in Firefox in a file on your system and be there after you close Firefox.