iphone alarm song not working

i just got a new iphone 15 and i've had nothing but problems with the alarm since i bought it, half the time it won't go off... or it will but silently. The alarm is extremely touchy and i worry it won't go off most of the time but i have found it will work if my phone is on sleep mode, face down, with the ringer on. However no matter which custom song i pick it will always play the default sound. I have deleted the alarm and made a new one. I have deleted and redownloaded the song. Nothing seems to work. i have been extremely disappointed in the iphone 15 and I probably won't buy from apple again. Not sure what is going on because all my phones previous to this one were great but for the price this phone has turned out to be quite useless.