How do i change the end date for my vat return?

Hello bobccook01,

You can chnage the end date of the return when selecting 'Prepare return' on the taxes screen > change the custom box for end date on the Prepare VAT Return screen which appears before submitting. 

If you are connected through MTD then you will not be able to change this end date as this is set by HMRC and sent through an obligation request to QuickBooks. 

Thanks