H4 to F1 and again COS from F1 to H4

I got my H4 visa in 2016 which was valid till April 2019. I joined a university in 2017, applied for F1 visa when I visited India in May2017 which is valid till may2022. I graduated in 2019 and again applied for Change of status from F1 to H4 in US and got approval notice. I visited India in march2020. Now I’m applying for H4 visa. Am I eligible for drop box?? What should I answer for “Do you have a previous H4 visa”?
Any one with similar experience and any idea would help!!