Mural settings are where you set the mural name, canvas color, theme, and (if you're working on a resizable mural) the mural size. It’s also where you can switch between the infinite and resizable canvas options.
To open the settings for your mural, just click the dropdown arrow next to the mural title and select Mural settings.
For more information, check out the articles change canvas size and change visitor avatar types.
Check out more MURAL vocabulary.