Right click - choose Rename...................

Right click on the filename and select "Rename" from the drop down menu. That
should correct your problem.

Thanks for the right-click advise. Turns out I was starting from
[Places] [Search for Files] [Look in Folder | Other] and the filename
was grayed-out. A second attempt from [Places] [Documents] and browsing
to it displayed an accessible filename. I was able to change it.

Next question: I was attempting to play videos from NetFlix.com but it
says [Linux] O/S is not supported. Are there any work-arounds for that?

You can also rename in the CLI (command line interface) using the mv
command... but I'm sure you don't want to do that - yet!

Another way besides the Rename command from right-click:
if the file icon is selected, F2 will open a miniature
box around the existing filename, and you can rename it
with the keyboard. Enter to finish. This and the right-
click way work the same way as does Windows.