I can not input a ←

[dongdong]

I want input in my doc， such as → ← ↑ ↓

that is a problem

[dongdong]

and more character I can not input

[dongdong]

like this

[UMNiK]

See

Use a different symbol instead of arrows for flashcards?

I like the new arrow dropdown for flashcard options a lot, but since I am using RemNote for mathematics, an arrow symbol is extremely confusing. Is it possible to customize a different set of symbols to indicate flashcard type, such as the “white arrows” or one of the sets of triangles that are available in Unicode?