I customize by turning off bookmarks toolbar, but when sign out of Firefox, then return to Firefox later the bookmarks toolbar is back, but do not want it.

"PersonalToolbar":{"collapsed":"false","currentset":"personal-bookmarks"}

This data is stored in the xulstore.json file. <pre><nowiki>"PersonalToolbar":{"collapsed":"false","currentset":"personal-bookmarks"}</nowiki></pre> ---- Try to rename/remove the <b>xulstore.json</b> file in the Firefox profile folder with Firefox closed. You can use the button on the "Help -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page. *Help -> Troubleshooting Information -> Profile Directory:<br>Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder *http://kb.mozillazine.org/Profile_folder_-_Firefox