Yes.., what you want to do is "transpose" your GW-7 to match your guitar player. The GW-7 will transpose +12 and -12 semi-tones.
However, the GW-7 doesn't have dedicated buttons to transpose on the panel itself. This parameter should be under the FUNCTION button. Press the FUNCTION button (this is the button to the right of the EFFECTS button). There should be numerous system settings you can change under the FUNCTION button.., and transposing is one of them.
Also..., you'll probably find more help on the General Arranger forum on the SynthZone (because the GW-7 is an arranger keyboard). Huge group of guys/gals there.., and some own the GW-7.., and some store owners who are also regular posters there sell it too. Good luck.
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