When you select from the third level menu, for example 1.1.2, it jumps to the third level menu of the next 1.2.1.

Example
1 Test

• 1.1 Test
  — 1.1.1 Test
  — 1.1.2 Test
• 1.2 Test
  — 1.2.1 Test
  — 1.2.2 Test