String or fetch

Hi
I have encountered a problem, that has kept me occupied the last couple of days. Please help me out.

I have a Form "new issue" (see attached). Previously we have typed in manually the field "submitted by", "from dept" and "email". I would like to enhance the form.

As the user inputs "submitted by", I would like the Form to Fetch the appropriate data / record from a new Form A, and automatically fill out "from dept" and "email", and display the data.

How do I do this? How should the New Form A look like.

Any help is greatly appreciated.
Regards

Dennis