When upgrading from v11 to v12, my modifications to the File Display Toolbar were not carried over. I had to perform a restore of a previously saved configuration from v11.
Your old toolbars are still there after you upgrade, they just get turned off initially to encourage you to look at the new ones, and for people who had not customized the old ones (who would then be stuck on them forever if we didn't switch them).
You can turn them right back on again if you wish, as the FAQ linked above explains.
The installer also shows a message about this when it happens, but you probably clicked OK instinctively without reading it out of eagerness to try the new version. 
For the File Display Toolbar, if you go here in Preferences and open the drop-down, you should find a File Display (1) option or similar, which will be your old version:
(Not needed, and may no longer be there, if you have already restored it another way, of course.)
[quote="leo"]Your old toolbars are still there after you upgrade, they just get turned off initially to encourage you to look at the new ones, and for people who had not customized the old ones (who would then be stuck on them forever if we didn't switch them).
You can turn them right back on again if you wish, as the FAQ linked above explains.
The installer also shows a message about this when it happens, but you probably clicked OK instinctively without reading it out of eagerness to try the new version. [/quote]
I read that and found my toolbar and turned it on, but for the File Display Toolbar I didn't know I had to go to Preferences>File Displays>Border (as you noted in your next post) to find that. Did the dialog mention that? It isn't there now after the import, it just says "File Display", but my modifications are there. Just intuitively, I would expect all the toolbar stuff to be in one place. I understand it now though.