The amounts that you can see in the summary report were based from the transactions you've recorded in QBO, olivia_phua.
If you might have noticed, you can only see the total amount of each boxes on a given period of time. You can run the GST Detail Report if you want to see the list transactions that comprise the amounts in each boxes.
Just go back to the list of reports and select the GST Detail Report. You can also visit this link from the IRAS for additional info: https://www.iras.gov.sg/irashome/GST/GST-registered-businesses/Filing-your-taxes/How-to-File-Tax/Com....
Keep me posted if you have other questions.