1.Right click on the lookup value that you wish to change and select Edit:

2.Click Yes to confirm:

3.Enter the new Value and click OK:

The value will then be changed:

Make sure you close thankQ and open it again for the change to take effect.
Note: You can also edit the names of some of the Lookup Value folders as well, for example the Profile Names:

Not all Lookup Value folders can be edited however. If you attempt to edit a lookup value folder name in those cases you will get an error message.