For some reason, Yamaha sets the default volume rather low on most of the voice presets.
To increase the volume for a voice, use the FUNCTION button to navigate to the “M.Volume” setting— or “Main Volume,” for the volume of the Main Voice— and increase it to the desired value.
There are also settings for the “D.Volume” and “S.Volume,” to adjust the volumes of the Dual Voice and the Split Voice, respectively.
There’s no way to change the default volume for the preset voice itself, so each time you select one of the preset voice numbers to use as the Main Voice, Dual Voice, or Split Voice you’ll need to adjust the Main Volume, Dual Volume, or Split Volume again.
After you set up the three voices, the effects, and the other Function settings, you can save them to one of the Registration memories. I think the PSR-E363 has only nine Registration memories, but you can refer to the manual to be certain.