Subscript or Superscript cannot be added in the Menu

Hello Team,

While developing a course I found this issue. In "Menu" I am not able to add subscript to the slide title.

Ex: H2O - Here "2" is subscript. There is no option to make 2 is subscript in the menu. Attached a screenshot for your reference. Let me know if there is any solution for this.

Regards,
Dipu