Update (22.11.2017): If you're experiencing issues on loading the page, it's not your fault most likely. Be patient is all I can say right now. Time to change the host.
When you hold CTRL and select "Edit" on the map you want to edit, the options that pop up when you first create the map will pop up again. This lets you change the mood, texture mod, and vehicle used (if using a multienvironment pack).