Help! Formatting has suddenly changed.

I’m using the screenwriting template and have just finished the first draft of circa 105 pages. I’m starting my second draft but notice that the formatting has suddenly changed - not for the old text but when I try to add new text into the old, it looks as if the page is divided into two columns. Also, the margins seem to have shifted more to the left (only for new text), and as soon as the text gets wider than a quarter of the page it breaks it up into a new line of text.

This same thing happened to me when I tried the fix for dual dialogue. The only thing that fixed that was to take out the special formatting but this time I didn’t make any changes to formatting - though I did use the “compile” function - but it’s never had this effect on my screenplay before.

How can I get it back to the old formatting? What went wrong? I didn’t change anything.

I’m grateful for all help.