Documentation
Changing page size
Page height or width can be set or changed manually by entering relevant values in the right-side menu. However, a much more convenient and intuitive way is using the "Stretch height" option which allows to maximize or minimize page height without changing the layout of all modules inserted into it.
It can be done by using the scale located on the left side of the page. To change the page height it is enough to click the scale in a required position (you will see the number showing the exact height you are on), and then fill in the "Amount" field with a relevant number of pixels (to minimize the page simply use a negative number). The page will be maximized or minimized in the area located below the point in the scale. All modules will be moved together with a page frame so it won't be necessary to place them all over again.
You may also use the blue "sliders" available at the bottom of a page and on its right side. The sliders allows you to change athe height and width of a current page, simply drag them to the required location.