Hello Andrew, this is Emily.
If you have connected your headphones with any other device (in this case, your iPhone), even if it is not currently connected, please go to the other device's bluetooth settings and find the headset listing, and remove it. Not just disconnect, but actually remove or forget it.
Then try to connect with the computer. Make sure you hold down the power button on the headphones for 7 seconds to turn on pairing mode on the headphones for it to be discovered by the computer.
I do notice that your Acer OS build is very outdated. In fact, it is a version that's no longer supported. Please consider updating it. You will need to update via here as updating via Settings won't go through anymore on outdated version. https://www.microsoft.com/en-us/software-downlo... On this website, click on Update now.