Are you registered for VAT in Germany as well as the UK?
If you're registered in more than one country I doubt QBO will be able to handle that without some serious workaround.
You should take professional advice on which sales need to be reported to which VAT authority.
If you want to keep all records in QBO, you'll probably need to have two independent QBO companies - one for each VAT registration.
I'd like to mimic part of what @paul72 is saying, it's defiantely worth taking some professional advice on which sales need to be reported to which VAT Authority.
From a QuickBooks point of view, i'll direct you to this article; which, when you've taken the professional advice, should help you decide which VAT code you need to use to achieve the outcome you are looking for; i'm certainly not qualified to tell you whether you should be deducting the VAT from your sales to DE.
A guide of what the VAT codes do: https://quickbooks.intuit.com/learn-support/en-uk/vat/common-vat-codes/00/239529
Hi I'm currently in the same situation as you. I'm vat registered in UK and Germany. Do you report your sales that charged Germany vat in same QB for UK, or do you have a separate QB for Germany?
Thanks for joining in this thread, @colourfulbw.
Should you need to set up another QBO company for VAT purposes, you can go to this link to choose your country, then select the right QuickBooks plan to get started.
Here's an article for your future reference: File and pay Tax/GST. It helps you learn about how to file and pay your taxes in case you'll need to for your Germany version of QuickBooks.
Let me know if you need more assistance. We're always delighted to help.