Thanks for writing in! By default, you can only set one global pattern in the theme options, X > Theme Options > Layout & Design > Background Options. Settings a background pattern in each individual pages can only be done with custom css. To illustrate it, please add the following CSS code in the X > Theme Options > Global CSS (http://prntscr.com/evui3r)
The code is an example to set a background pattern for pages 1,2 and 3. As you can see in the code it is using the
n is the ID of the page. To know where to get the ID of the page, please check this out: https://theme.co/apex/forum/t/setup-how-to-locate-post-ids/59
Hope this helps.