I'm not sure I understand.
In your keyword test, you have a browser loop that executes a browser for a URL. That URL... is it set to a Variable in the loop or, after the loop starts, you get prompted to select the value? I'm not sure I understand how things are working in your test.
The variable contains a string (URL) which the user can select in the Browser Loop operation. That's the start of the main loop. There is no prompt to select anything.
OK then... what I indicated still stands. Whatever variable you use when setting up the Browser Loop operation, utilize that variable throughout the steps within the loop. Basically, any operation that takes a parameter you can set that parameter to reference a variable for the value. This includes property checkpoints, if then statements, Keys, SetText, and other similar operations.
