Struggling to create a new line in a formula


This ought to be really easy but I cannot seem to work out how to do this.

Every time I try to create a new line when editing formula, in an existing formula by hitting enter, it just runs the code, instead of creating the line.

I have tried using notepad to create the formula and copying and pasting the whole thing in but it doesn't seem to work (possibly formula is wrong) but how do I create the new line? I am using a windows pc if that helps.