Bluetooth volume issue

Hello:

I have a UE Boombox and when I try and connect my Iphone 5 or my 5S the volume will just crank to maximum out of now where, yet I have an old 4 that works perfect, also my Ipads and surface all work fine.. It's just my 5 and 5s, I have everything updated, does anyone have a suggestion? Also using just my headphones with these two phones it's fine, it's just when it's connected to bluetooth....

Thank You