Very sad and disappointing to hear that.
I use a Samsung 5 Ultra and have this watermark too, and I have no idea how to modify my bios.
I cant be possible that I, under recommendation of microsoft, have updated my windows and nos have got an usseu that I have to solve by myself?
What kind of upgrade and support is that?
I am totally disappointed after telling everyone that they should use windows 8 and now having to experience that.
I wisely wont recommend windows 8 again, why would I recommend an OS that messes up someones pc?
=(