The location of the selected hall in the hall settings dialog is replaced with the one on the left by clicking the shift left button.
Location of the Shift Left Button
Select the hall where you will scroll and click the right mouse button. Click the Properties line from the right click menu that opens.
Enter the hall settings.
Select the hall you want to slide from the list of halls.
Click the Shift Left button.
The hall you chose will be replaced with the one on the left.
Before Shift Left
Choosing the hall to shift
After shift left