I use the menu tab under content. My current menu structure is as below
MainMenu
Sub menu Level 2
Submenu level 3 (1)
item 1
item 2
item 3
Submenu level 3 (2)
item 41
item 5
item 6
What I want is as below
MainMenu
Submenu Level 1
Sub menu Level 2
Submenu level 3 (1)
item 1
item 2
item 3
Submenu level 3 (2)
item 41
item 5
item 6
Please note that I want to add a new submenu under MainMenu and want the previously added submenu and every thing under it to come under the new one.