Highlight only when filling the document

Check this sample PDF: https://framadrop.org/r/XUVMGiSP6X#23i8yLMI5lkWUoXd2yZoDl4ePShwrokZU1c67mglSXI=

Can you share (part of) this document?

What software the receiver is using?

Hi.

You can set this for a computer (1 user) : Acrobat : Preferences : Form

And you can set it for a PDF form (any user) by adding this JavaScript as a (startup) Document Script :

app.runtimeHighlight = true;

If you want to modify the default color too, you must add this line:

app.runtimeHighlightColor = [ "RGB", 1,1,0.8 ]; // light yellow

Moving this to PDF Forms