Hi david259,
Thank you for reaching out to us.
The GST amounts showing on your BAS is based on the transactions with GST on it. You can check the transactions entered on a particular period and ensure that it has the correct GST on it.
However, if you have lodged your BAS already and made any changes to that period since the lodgement will automatically appear as amendments to that BAS. You can run a report called GST Amendment report to check the amendments.
You can also have your BAS unlodged if you would like to adjust the BAS amount by contacting our support team: https://quickbooks.intuit.com/au/contact/.
For your reference, you can also check these articles:
What to do when BAS amounts look incorrect
Can you please tell me how to make a GST adjustment for the BAS
Feel free to leave a comment below if you need any help. Have a nice day!