The underlines on the text for the toolbars is controlled by a setting on the Options menu from the FN desktop.Select Options | Remove & from Tool Bar Text.
If the menu is checked then the "&" will be removed. If the menu is not checked then the "&" will be in the text. The "&" is what causes the underline to appear.
On some display drivers the "&" appeared instead of the underline. So this option was added to remove the ampersand ("&") from the text. However for normal display drivers, if it is selected(turned on) then the underline will not appear.