You've come to the right place for answers, @mkalaluka. I hope you are well today.

I'll ensure you can activate the number sequence for your invoice in QuickBooks Online (QBO). This way, you can easily track them. 

First, change the settings and turn on the Custom transaction numbers feature from your Account and Settings. This way, you can control the sequence. Here's how: 

1. Go to Settings ⚙ and select Account and settings.
2. Select Sales, then select anywhere within the Sales form content section.
3. Turn on Custom transaction numbers. 
   
4. Select Save, then select Done. 

Once done, you can now manually add the invoice number. QuickBooks Online will remember the number and continue the sequence number you want.

If you would like to review the invoices you made, run the Invoice List. Pull this up by going to the Reports menu at the left pane, then type Invoice List on the search bar. 

Check this article for more information: How to change the invoice number on sales forms. 

Additionally, when you use this feature and decide to turn it off after setting up your desired invoice number, QuickBooks will begin assigning consecutive numbers to each new invoice you create. 

You are welcome to visit us if you need additional help with invoice numbers or anything about QuickBooks. It will be my pleasure to help. Stay safe, and have a nice day.