@Mariella ******
really quick recap
the OA visa you show proof of funds in YOUR country (meaning you don't bank any money here
the OA visa is a year-long, unlimited entry visa that gets you stamped in for a year each time (or as long as your mandatory 100K USD health insurance is valid for) during the validity of the visa
Down side, you need police background check, medical certificate, mandatory 100K USD health insurance and you can only get it in your country before you wing your way here
Another benefit is you can get almost 2 years of stay out of that OA visa that's valid for a year (by exiting and re-entering just before the visa itself expires and having a new year of the insurance)