According to the very simple instructions select a layout ( in my case header-bottom) then click menus and toggle all those pages you want to use this layout. Done this and it always reverts to the default layout not the one I select.

Hi,
unfortunately, I can not fully understand your problem because of my bad english.
I found the following sources, maybe this helps you.
Link to Warp 7 documentation
Video in englisch showing the steps to use a Layout
Note the section in the video in that the author saves his changes - maybe you forgot this step?
Greetings,
Christian

Hi there,
first at all, please delete all layouts you dont need.
Here are more instructions how to handle the layouts
www.joomlaplates.com/support/documentation/warp-7-layouts