how do i replace the upper strut mounts

You remove the entire strut assembly, compress the spring with a spring compressor, then disassemble the strut and replace the upper mounts. This job requires special tools and if done improperly, can be very dangerous, so if you haven;t done this, I suggest letting a professional do it for you. Here are some near you: https://repairpal.com/volvo-repair-in-portales-new-mexico