You can drag the Bookmarks Menu button that shows the bookmarks in a drop-down list and drag the Library button that gives access to recent bookmarks and history from the Customize palette to the Navigation Toolbar.

• https://support.mozilla.org/en-US/kb/customize-firefox-controls-buttons-and-toolbars

The Bookmarks Menu button has a "View bookmarks sidebar" menu item.

See "How do I add the Bookmarks Menu button to the toolbar?"

• https://support.mozilla.org/en-US/kb/bookmarks-firefox
• https://support.mozilla.org/en-US/kb/use-firefox-sidebar-access-bookmarks-history-synced

Thank's for reply but I don't want to open library, i know how to open Library with shortcut Ctrl+Shift+o or add it to Toolbar, but I want to view my drop down Bookmark list that I was getting when I clicked on Bookmark icon from the Toolbar (please view uploaded image for the old icon from the first message).

My reply has two parts, the first is about the Bookmarks Menu button and the second about the Library button. Both these buttons are in the Customize palette by default and can be dragged to the toolbar, so do not get confused. You can drag the Bookmarks Menu button that shows the bookmarks in a drop-down list and you can drag the Library button ... to the toolbar

• https://support.mozilla.org/en-US/kb/customize-firefox-controls-buttons-and-toolbars

• https://support.mozilla.org/en-US/kb/bookmarks-firefox

usually I use right click on toolbar and select Customize Toolbar, but the Bookmark Menu icon didn't appear among the offered icons. Now I downloaded a new update and all work fine, thank's for help.