Trying to submit VAT return but only showing Dec not Jan & Feb?

Hello and welcome to the Community, c_edkins

It's only possible to have one open VAT period at a time in QuickBooks (the successive VAT period will become open once the current period has been closed, either through submitting to HMRC, or by marking the return as filed). 

You can check how much you owe for other VAT periods at any time by running the VAT liability report. 

For further information on VAT in QuickBooks Online, see here. If you have any further queries, get back to us below!