Script for immediate menu updates
Is there any way to new user actions, made with create custom action, to be written to the disk without exiting Daz. I tried content library/scripts/utilities/update and merge menus.dsx but it didn't save the changes to disk. I don't know how many times I've created a custom action and continued working only for Daz to crash before I exited and reloaded. And thus the custom action disappears until I create it again.

Comments
Window>Workspace>Save Layout, which will give it a name. The session layout (the state that persists from one session to the next) is saved only on shut-down, I believe, rather than being a user-triggered action.
Saving the Layout, as Richard described, is also good for saving the location of Panes (Tabs) in the interface, if you add, delete, or move them around, dock or undock them. Same goes for Toolbar changes you make.
I didn't try save. I tried Export. Export didn't do custom actions.