Congrats on your SE - the wah isn't global; you have to select wah from the pedal section on each patch and save the patch with this setting. If your patch already has another pedal option, you can only choose one pedal option at a time. So, if you have a patch that has uni-vibe, you can swap the uni-vibe for wah-wah - but you can't have both.
Have you read the manual for this yet? If you don't have one, you can load a copy down from here:
http://www.voxamps.com/support/manuals/"I started out with nothing ...and I've still got most of it left!" (Seasick Steve)
