Problem updating Musescore 2.0.2 to 2.0.3

Hi
I have been ruing 14.4, 32 bit and have been using Musescore 2.0.2 I would really like to upgrade to Musescore 2.0.3. ( amateur musician)
I have been unable to do this
I am new to linux and was advised to use:-
Sudo add-apt-repository ppa: mscore-unbutnu/mscore-stable
This seems not to work
If I go to Musescore web site, I can, and have, downloaded for Ubuntu museScore -2.0.3- i686 appimage
but not sure how to proceed
Any advice greatly appreciated.
Allister

I may have put this post into another thread as well,sorry.