local files wont disappear on ipod

[Mawia]

hello everyone, so ive got a problem with my ipod syncing local files. not that it doesnt work, rather it does it without me telling it to. so i have a couple songs on itunes, theyre not shown in spotify as local files.all good. now when i sync my ipod wiht spotify, those local files get transferred to my ipod, not the spotify version. but i want the spotfiy version! because my ipod also has this problem with local files that everytime one comes up, it will lower the volume after a couple seconds. and then after the song ended, it only skips to the next one, if the next one is a local file as well. oh and right now it doesnt wanna play local files at all. anyway, why did my ipod sync those files that werent even in my pc spotify and how do i get them to disappear? and if anyone has a solution for the other problems as well, thatd be great, but im not expecting that.

thank you!