I movie problem

Can someone please help me, I upgraded to iOS Capitan on my I mac and went into my i movies and it as all changed, the format, the way it looks and the whole editing system, why do Apple do this and screw up a day I could of used better. Apple just seem to make these changes and I am not that tech savvy and constantly after every upgrade many programs seem to change with no warning that is explained in a way that should make you really consider whether to upgrade. I am told to upgrade all the time because if not it can effect your system, so does any one know how i can get back to my older version of I movie and find all the editing functions as I had before for adding music and actually seeing the process so much easier,

Thank you to anyone with any advice

Paul