@adi47 , since your original entry in 2018 was with F1 -- you enter that date as your original entry , ignore being out of the country for vaca/ school closure. This is for the years 2018, 2019, 2020
for 2021, you still show your original entry date with F-1 and report the change of status and the date thereof as required on line 1b.
Does this make sense ? Is there more I can do for you ?
pk
