Insert user name into a record

In Events - Global Pages - Login Page - After Successful Login
Put in your session like this:
$_SESSION["UserName"] = $data["username"];

Then in your Fields - Whatever table for your Username field click on Properties Box Pick Readonly Then in the Default value use $_SESSION["UserName"] Or click on the ... and in drop down at the top pick Username and it marks it for you. Same for add and edit.

The easiest option is to use BeforeAdd/BeforeEdit event and update that field value behind the scene.

Sample code:
$values["FieldName"] = "some value";

Instead of "some value" you can either use a session variable as @Tandy suggests or you can use Security API.

$values["FieldName"] = Security::getUserName();

More info:
https://xlinesoft.com/phprunner/docs/secapi_get_user_name.htm

I would like to thank you for the replies, it has solved my problem.

I am not a programmer of any sort, and I'm learning as I go, and having help is really great.

So a big thank you!

Steve