Sorry about this - I should know the answer - but its foxing me on what the fix is.
I have used one of the freeway templates and everything works well - as I move through the menu options the pages do NOT jump around - so long as the content is exactly the same.
If I put in some new text on a page that is unique to that page it alters the height of the page (very minimally) and as you go through the menu it means you have one page that is not the same as the others (i.e. a fixed height similar to others).
The movement is generally caused by the Browser creating a scroll bar that shifts your page by 8-10px.
If you want to avoid this you can ‘draw’ an empty graphic container at the bottom of any page that is not tall enough to create a scroll bar so that all pages have one.
I can have just one paragraph of text in the centre (using the Clouds Template from PRO version).
On another page I can have same paragraph with an extra line underneath that paragraph - plenty of space left in main body of page - and still it alters from page to page??