@JanetSilb_Spike
You will probably need to set the default value in the feature template for it to behave as expected. I suspect that you will need to do this from the map viewer classic unless that field already has a default value assigned in its feature template, then you could manage it from the Field Maps Web App.
When editing the feature templates in map viewer classic, there is no need to save the map, just save the templates.
Edit Session -> Manage
Edit Default Value then save templates
- Justin Reynolds, PE