How do I format this field?

When you click on Show As it will take you to the Formula editing window. From there you can just select the field name you want to show, i.e. Customer.Name.

I've never tried putting a formula in a Show As. I just use the field names that I want to show. I can do a concat of field names.

That is confusing. Like I said earlier, it looks like a typical formula window, but if you just add the name of the field you want to show then it will just show that field. Select the field that has the data in your screenshot "Kari"  in it. Just the field name and nothing else. It will then show just data and not the Name and percentages.

Of course, maybe I should ask what data are you trying to show here? What field are you trying to default to?

Since there is no error message, the field name is valid.

I'm stumped. Maybe someone else has experienced something similar.

"Show as" is indeed a formula field. But it has an effect on the "Popup" "Show as" option only - yep, two "Show as" fields on the same panel. If you select another option, then its content depends on the columns selected in "Edit columns". Those idiosyncrasies are what makes Ninox so lovely.

Yep I have had this issue in the past too wher my field name is '118 xxx etc')

mainly got this error when i typed the field name!.

so usually it menat i have to cancel - save - come out off the form.

Go back in and pick the neame from the list (not type it )

then quite often it accepts it!

If you make the field, for instance, a Combo box, its content is determined by the columns selected in "Edit columns" since it is not a Popup. You can always add a "formula" column, and put anything to your liking in that formula.