When I click on the double arrow to the right (or left) of the page breakpoint line to allow page to expand elements move around. Here's the page in Muse
and here's the page preview
any suggestions on how to fix assets in place when page expands. I've already made them "responsive width and height."
To help us investigate your issue, can you please publish your site and share the URL with us over here. That would help us better understand the nature of your issue.
Just in case you haven't had a chance to do so, I suggest going through this tutorial Create a responsive website | for insights into what could be causing the issue.
The site has been published at trlproductions.org. I made it unable to extend because of the elements relocating.