Return filing periodicity for current year turnover more than 1.50 crores

Sir, further to my original query, can you please clear my fresh doubts.

I filed quarterly return for first two quarters of FY 2018-19 because I had opted for quarterly return since my turnover in preceding financial year was below 1.50 crores. However, in the month of November'18 my turnover crossed 1.50 crores to be 1.63 crores. But since my option was to file GSTR-1 quarterly, I continued to file the third quarter's return as quarterly. Because change of frequency is only permitted at the beginning of a quarter as I am told. My turnover till 31.12.2018 is Rs 1.83 crores subsequently.

Now, in the fourth quarter, for the month of January'19, due to turnover in current financial year being more than 1.50 crores, when I tried to edit my option to switch back to monthly return, it didn't allow me and this error message popped up :-

"GSTR1 form is already submitted or filed for one of the return periods in 2018-19,hence edit of preference is not allowed"

I am totally confused. How can i file my return for January'2019 as monthly since it does not allow me to do so?

Please do guide me. Would I need to file one quarterly GSTR-1 only for  whole of the fourth quarter to end on 31st Mar'2019 or do I need to file monthly returns for Jan, Feb, March ?