I have been trying out the tabs set to buttons and have three rows. I just brought up the Customise Toolbars dialogue and when I clicked on “Use Large Icons” or “Display Macro Titles in Basic Toolbars” the three rows reduced to a single row
I reproduced this issue, but after you dismiss the “Custmize Toolbars dialog”, the buttons go back to three rows, so it is not a big issue. Nevertheless, I might fix the issue in future versions. Thanks!