Thanks vor your almost realtime answer! 

Your solution didn't solve the problem. I made a mistake in my original report, "Review" and "Advanced" appear (at least now), but no "Assment quality" left to add, at "Ribbon Customization" under "View". I have made two significant screenshots, (with hi res back, because it was unfortunately not a problem of resolution), from "View" and from "Review".

Under Track Changes the black arrow right under "Reject", open this windows:

Nice WE,

Rosa Alcalá

Hi Rosa,

I don't believe this is a known issue... in fact I have a new laptop coming in a couple of days and this will be W8.1 since we don't support W10 internally in our business yet.  So I hope not!!

I think if it was me I'd try a complete reinstall before contacting support.  If you want to try it do the following:

1. Uninstall Studio 2015 and MultiTerm 2015 through the windows control panel
2. Now manualy remove the following folders if any of them are still present after the uninstall:
   c:\Users\[USERNAME]\AppData\Roaming\SDL\SDL Trados Studio\12
   c:\Users\[USERNAME]\AppData\Roaming\SDL\SDL Trados Studio\12.0.0.0
   c:\Users\[USERNAME]\AppData\Local\SDL\SDL Trados Studio\12
   c:\Users\[USERNAME]\AppData\Local\SDL\SDL Trados Studio\12.0.0.0
   c:\ProgramData\SDL\SDL Trados Studio\12
   c:\ProgramData\SDL\SDL Trados Studio\12.0.0.0
   c:\ProgramData\SDL\SDL Trados Studio\Studio4
   c:\Users\[USERNAME]\Documents\Studio 2015\Project Templates

Then reinstall.  If it's still a problem after that then I think the best thing will be to contact the support team.  

Go to the Knowledgebase;

http://kb.sdl.com

Then go to the tab called Solution Finder and now go here;

Download & Installation Problems
- I use SDL Trados Studio and/or SDL MultiTerm 2009, 2011, 2014 or 2015
-- The installation went fine but now I get an error message etc
--- The problem occurs in (pick the appropriate tool/s)
---- None of the articles resolved my problem (if they didn’t!)

Follow the route for your problem and if there is no answer that helps by the time you get to the end you'll be presented with a form to contact support. Complete all the fields in the form making sure your email address is entered correctly or nobody will be able to get back in touch with you.

Also use the Chrome browser to log the case if you have it; you'll get more success in completing the form.

Regards

Paul