Why has net enterprises changed my declaration from monthly to quarterly

I have registered with net enterprises and made an initial blunder i.e. ticking the wrong box re monthly/quarterly declarations and declaring my first 3 months income under a one month declaration. Thereafter it was on a monthly basis, i.e. Oct turnover, declared by Nov 30th. No problems until the end of Dec when I went on-line to declare my turnover for November and it then only offered a quarterly declaration - nothing required until end of January.

So I entered in my November turnover in the hope it would allow me to progress but it is still sitting in my net enterprise account as virtually in progress - obviously if it does process this amount it would only be for my monthly turnover (Nov). I went back in tonight to take a look and the declaration is still sitting there, it seems to offer me the option of changing it - I have not yet touched the button to do it, as I will wait until the 30th of January to do this.

However, I will only be able to declare Novemeber and Decembers turnover, as I do not have 3 months turnover to declare because I was previously declaring monthly. My question is this, am I right in assuming that I only need enter in November and Decembers turnover for this supposed trimestrielle? Your excelent video helped me in 2 ways, i.e. I do not need to send in the paper dec rec by post from RSI as I am doing it on-line and the reminder of the pro rata quarterly amounts.