How to set my desktop as the default desktop?
This should do it:
You don't have to specify a desktop, just check the setting. But if you do specify a desktop, it will be remembered.
We have a similar setting for workspaces:
For the workspace one, you have to actually create a workspace in addition to checking the setting. Then the workspace saves and auto-loads next time you open Toad.
Desktops refer to docked windows like Object Palette, Output window, Code Snippets, Project Manager, etc.
Workspaces refer to connects and MDI windows in Toad (Editor, Schema Browser, etc, and for these windows (but not all), the content of these windows too - open files, object being displayed, etc).