imap synchronization (gmail) within Thunderbird

i have personal folders i have added to gmail using Thunderbird to save various emails. the "all mail" and "important" folders are filling up with the duplicate content of my saved emails in the various personal folders. if i delete the content in "all mail" and "important" ---it deletes the emails in my personal folders. i tried unchecking my personal folders in advanced synchronization to try to un-link the folders but it still deletes my email when i clear out these duplicate emails in "all mail" and "important". when i save an email to one of my personal folders---how can i prevent a "linked" copy from being stored in "all mail" and "important"? Thanks!