It's normal for the default toolbar set to be changed to display the (new) default toolbars when installing a major update (i.e. 11.x -> 12.x).
If you are using a different toolbar set in some places, instead of the default set, then that might be why you didn't see it happen. If you import an Opus 11 configuration backup (instead of just installing 12 over the top of 11) then that might also be why.
For most people it should be as per the toolbar/upgrade faq, but there are so many ways Opus can be configured that you might have seen something different.