Hi, thanks for sharing that great picture of your uncle Bob.
I’ve taken a while to get back to you because I’ve been busy with my day job and academic studies.
It’s slightly difficult to know exactly how to help because there are different ways to play the keyboards. However, here is a method that would work for most players, and hopefully for Bob. Maybe you can print it for him or write it out.
First, you need to set the left hand accompaniment to work the way he likes. Most usually that would be as follows.
In the Auto Play Chord section press “Mode” and select the left hand playing mode.

Usually, you will set it to “Fingered” with Memory on.

Next, turn on Music Style Arranger. By doing this, Bob won’t need to set the right-hand sounds. Appropriate sounds will be set to suit the rhythm (and he’ll be able to change them but it will give him a reasonable starting point).

Next, choose a Rhythm in the style of the song you wish to play. To do that you select a Rhythm Group and then select a Rhythm from the main screen. Note that there are page up and page down buttons where you can select additional Rhythms.
Now press start and off you go.
Another easy way to set things up is to select the Rhythm you wish to play. Then, press and HOLD the One Touch Play button for three seconds. This sets up the entire keyboard.
A third easy way is to set up the entire keyboard is with the Music Stylist button. Press the button and then select the musical category or era. You can then scroll through the list to select the sort of music you wish to play. As you scroll through the list the keyboard setup will change to reflect your selection.
When Bob finds his most favourite setup it should be saved in the Custom Panel. It will then be retained when the keyboard is turned off and can be recalled by pressing the Custom Panel button.

Refer to pages 8 and 9 of the manual to see where these buttons are. Pages 8 and 9 are a quick reference and they tell you which pages in the manual to flick to for more quick help. Rely on these pages 8 and 9 to help you the most.
Good luck and please let us know how you get on.
Kind regards,
Mike
If architecture is frozen music then music must be liquid architecture. Quincy Jones