Saving heading in main window panes

To save the changes, Settings > Set Lister Defaults, and then save the Folder Format there.

Alternatively, it can also be done this way, which also goes into more detail about how things work: Folder Formats: Quick Guide

Also, if you want changes like that to be saved automatically for individual folders (similar to how File Explorer works), Preferences / Folders / Folder Formats / Automatic Formats lets you do that.