HOW CAN I ADD A TAB GROUP TO THE TOOLBAR LIKE i USED TO BE ABLE TO?

I used to be able to create a tab group and then name it, then add it to the toolbar so I could just click on it...I have no clue how to do this anymore! I created a new tab group as the Mozilla help suggested, named it Tab 7 and now all I want to do is add to my other tab groups on my toolbar. Help! When I click on the arrow to the left side of the existing tab group, all is gives me are the exisiting web sites in the new tab group I created---doesn't list all the tab groups I had previously created. Thanks for any help!