My clients' UK based companies have home currency in USD as 100% sales and purchases. I am having issue with VAT report as it shows USD instead GBP. Please advise.

Thanks for actively responding, @h-jiang-kingsman. I understand the need to change the home currency to GBP to show the VAT report in GBP currency. 

Please know that when you turn on the multicurrency feature, we're unable to change your home currency. 

As a workaround, you'll want to completely delete all data in the company file and start over. This option is only applicable if your account is active for less than 60 days. Then set up the home currency to GBP to run the VAT report you need. 

Here's how:

1. Sign in to your QuickBooks Online account, then look at the URL in your browser's address bar. Delete all the text after the last / and enter purge company.
2. To confirm you want to delete your company data, type Yes.
3. Select Wipe data.

You can also follow the recommended solution provided by Fiat Lux - ASIA. 

On the other hand, if your account is active for more than 60 days, you can no longer purge your company data. You have to cancel your account instead, then start a new subscription. 

Check out the detailed steps shared in this article: Delete QuickBooks Online data and start over. 

Feel free to get back here at any time if you have more concerns. Take care!