changes sounds by itself???

[al urezzio]

maybe someone has experienced this too & can help .. i use my "Favorites" to save the many styles I use for my original songs & the voter tunes I play . Recently , i pull up a song ,started to play & noticed some things different within the styles , snare drum was different & way too loud , a horn had changed to a harmonica Etc . didn't notice it happening throughout the favorites , just here & there .. is there any reason for this to happened & is there a way to prevent this from happening ..?? thanks in advance