Saving all our accounting transactions and attachments when creating a 2nd QB account

We have been running QB online version uk since 2018.  Every invoice we send out to customers has up to 5 attachments.  Every supplier invoice has a copy of the actual invoice attached.

We have just started trading as a Ltd company so have had to get another QB.

How do we extract all the data from our original QB's, for reference and for complying with HMRC keeping your documents for 7 years?.  We don't need to keep the original QB open once every one has paid. They are being treated as 2 separate companies.

Any advice?