render dropdown single select as image

hi, I have a dropdown "rank" with values:
Profile Value Layout:
but in this way [value] is the label, not actually the dropdown value

i solved using this layout
<img class="" alt="[value]" src="/images/rank/[fieldname].png"/>

I just can't remember how to set a default value for this field for all the users (even the users who are already registered)

You can use IF substitution to set a default using the layout parameters. Example as follows.

[cb:if cb_myfield=""]Default[/cb:if]
[cb:if cb_myfield!=""][cb_myfield][/cb:if]

The default at registration parameter only functions at registration so it won't affect existing users.