You wish to create a custom format for your Access logs, however some of the ELFF formats do not have a corresponding custom format
 

In order to add a field to the custom format you will need ones that begin with % or $.

Since fields like cs-uri-scheme do not have a custom format, adding cs-uri-scheme will not return a value, it will just display the field name itself.
In order to display a value you will need to edit the format to the following

$(cs-uri-scheme)

Other examples;
$(c-ip) $(cs-username) $(localtime) $(cs-request-line) $(sc-status) $(sc-bytes)