@help I have made some customisations to the theme I am using, and some of these customisations are lost whenever I update a plugin or reasons unknown!

What would be the best way to back up the changes to the theme?

@jrr The best work-around for now is to do this: before making changes to the theme, go to Account → Edit Custom Themes → New Plug-in. Then when you edit a template, it will copy your changes into the plug-in that is just for you, preserving things when you update the theme. I want to make this automatic in the future, sorry for the trouble!