How to set default image for display?

I want to have a default image selected and then displayed if user doesn’t pick an image.

I see 2 advanced default image fields, but how do I use it?

Please paste the EXACT code that is required?

Field is like this:

post_banner_media_intro

Field names are in advanced tabs and the texboxes are:

Default Value

And

Set Default Value via Parameter

I’ve looked for and answer for this, but all I could find were cryptic responses from developers!

very clear way to do this would be appreciated!

https://pasteboard.co/FvFLSQRsz0kY.jpg