To create a list of pages in the main menu instead of the only Text / Gallery/ Video Page:
1. Create a New Main Menu Page pressing the +Add Menu Item button.
2. On the page select the New List Page from the Child Page drop-down list and then save the page.
3. Drag-n-drop the existing Text page under the newly created section.
4. Now it's time to update the section that was previously created and existed already. On the Main Menu page change the Child Page type and save it.
5. Now you can add various pages under the section without the need to make any changes to the main menu. Also, you can drag-n-drop the Text page back so that it exists along with the other pages in the section.
6. Publish it.