Can't adjust volume on individual song , itunes 12.7.4.80

I can't adjust volume of any individual track .When I go to adjust the volume of a song and move the volume slider left or right, click ok and exit, I find that when I re-enter the file, the volume is back to the original level it was prior to my adjustment. It happens only when I try to adjust a single track while it doesn't happen when 2 or more tracks are selected. Any help ?

Thanx.