First of all, thanks very much for the follow up - appreciated.
I spent quite some time looking through menus, pdf docs, you tube videos et al. I thought that something wasn't quite right because speed was not one of the 16 displayed 'My Motorcycle' data items shown on my Nav 6. The You Tube video that I'd seen shows how to rearrange the displayed data items such that you can get a single display of your 4 chosen items and then (by scrolling the wheel) another single display with 2 and then finally a single display with just one item.
I managed to contact the Tech who dealt with my problem and, all credit to him, he knew how to resolve it but I have to say that I think the available documentation leaves a lot to be desired.
Firstly, the doc does not explain how to customise the My Motorcycle display. Second, and most crucially, the doc fails to mention that there are potentially more than 16 data items available for display within the My Motorcycle screen.
What you have to do is customise the 1st display slot on the first row of 4 display slots to be the data item that you want displayed on a single screen. What isn't apparent until you try, is that 'speedo' as a data item is available within the list that you select from but it appears near the bottom of the list and is not included in the default 16 items shown on a brand new unconfigured device or, as in the case with mine, a device which has had a hard reset. I had assumed incorrectly that the 16 data items shown were the only items available for display on the single display.
Thus, you can go on to configure the 2nd data item on the first row of the 16 to be what you want and then items 1 and 2 will appear on the display that shows 2 items. After configuring items 3 and 4 on the first row, the 4 items now on the first row will be the ones shown on the custom display that displays 4 items.
After doing this, when you push the jog wheel sideways to get into the 'My Motorcycle' display, scrolling the jog wheel will then cycle between displaying 1, then 2 then 4 then finally all 16 of the configured items.
In my case, I have speedo as display 1 (showing 1 item), speedo and range as display 2 (showing 2 items) and speedo, range, front psi and rear psi as display 3 (showing 4 items).
So, happy chappy now until I get stuck on my next challenge (which is sending a location that you have found on your phone into the Nav 6 as a destination
)