How do I make my page fit A4?

It’s printing too wide so the left side of the page is cut off. I have three columns but if I make them narrower then all the text is out of alignment with the other columns. I am REALLY stressing if I have to retype is all or somehow shrink it and reallign every line with eachother. I have twenty pages of stuff to do that to!

I’ve heard something about PDF format? But I don’t know how to do that kind of stuff.

How can I avoid this issue in future? Is there some setting I should apply to the page?

Please help, it would be VERY aooreciated.