Think of

I think about cleaning the dishes.

Okay,
What does it mean to say "we thought of settling that issue"

We thought about settling that issue.
We had the idea of settling that issue, and considered it.

JumanahI think of cleaning the dishes.

Sometimes I do too, but I never get around to actually doing it.

we are thinking about settle that issue.

Anonymousthinking about settle

'about' is a preposition. The only verb form that is acceptable after a preposition is the -ing form.

Therefore, 'about settling' is the correct combination.

CJ