I want to use the document.getElementByID method to change the text of an element.
It works and replaces the old text but the new text is lower down when I want the new text to be on the same line.
It's impossible to tell what the problem is from that description. Post some code and then we might get a bit further.
My guess is that you're not replacing the text node itself but the entire element, but we'll have to see.