FM 10 Tab Scrolling Arrows Disappeared

[Nancy Allison]

Hi, all. I'm using FM 10 on a Windows 7 system.
 
I'm sure I've accidentally changed a setting, but I have no idea what I've done.
 
My books typically have 10 or 12 chapters and I usually open all the files at once. They are represented by tabs across the top of the workspace, and there used to be scrolling arrows on either side so I could scroll to tabs that weren't in sight. Now those tabs are gone. I found them useful and I want them back!
 
The only unusual thing I've recently done was open a book, save it under a new name, and regenerate the book. Of course, the previous TOC and IOM files dropped out, so I deleted them from the book and generated new ones. After a while I noticed that the scrolling arrows were gone. I've closed and reopened FM and also rebooted the system, to no avail.
 
Does anyone know how I can get those arrows back?
 
Thanks.