compizunityworkspace-switcherworkspaces
Press super+s. You should see your 4 workspaces. Move your mouse, go over another workspace other than that which you were in. Press super+s again. You should go to the workspace that had the mouse over it not back to the one where you started.
I can't do that anymore. It goes back to the first workspace. How can I correct this?
In Xfce 4 you can define multiple workspaces by either adding a new wokspace switcher to the panel, as it has been done in the question, or by using the workplace switcher that is already installed in the lower right corner by default.
With a right click on this swicher you can select the switcher properties. Choose more than 1 row to have more than 1 workspace.
Moving applications to another workspace can be done with a right click on the application's top title bar and select Move to Another Workspace:
Number and names of workspaces can be defined in the Xfce 4 Settings Manager (from Applications -> Settings):
Okay, I have found the answer. Settings - Window Manager Tweaks - Workspaces - Use the mouse wheel on the desktop to switch workspaces.
Best Answer
Best way to switch workspaces is
Ctrl+Alt+←↑→↓
and
if you want to switch an opened application to other workspaces:
Ctrl+Shift+Alt+←↑→↓