How to fix Spotify having 1:1 volume with my phone, when I'm listening to music on my computer.

my Iphone makes it's volume whatever my spotify volume is on my desktop. this means everytime my phone makes some kind of connection with the app while its running in the background or opened my phone will now at max volume spew whatever opens next,, all with 0 input from myself. It happens 100% of the time and frankly I don't know why. and the best part, I cannot lower the volume, it just lowers my spotify volume, and it doesn't show it but my phone's volume is now hidden behind the spotify volume, and I can only change it once I close the app. Both the volume rockers and the pull down tab from the top right are useless and maxed out just because i use spotify on my desktop and have the app on my phone.