I am wondering how to change my invoice numbers, I don't see the option. Thanks

I've got all the steps to help guide you on how to change your invoice numbers in QuickBooks Online (QBO), Nick.

QBO generates invoice sequence numbers by default, but you can always change the invoice number by your preference. To do so, you'll need to enable the Custom transaction numbers feature from the settings. I'll guide you on how:
 

1. From the Cog Wheel, click Account and Settings.
2. Select the Sales tab.
3. Tap the pencil icon from the Sales form content section.
4. Toggle on the Custom transaction numbers. 
5. Save once done. 

After that, let's alter your invoice number by following the steps below:
 

1. Go to Sales and select Invoices.
2. Open an invoice and click Edit.
3. In the Invoice no. field, enter the custom number or letter sequence you want to use for your forms. The number you set here will follow the sequence for your future invoices.
   
   
    
4. Press Save or Save and close.

See these resources to learn more about setting your own numbering preference and personalizing invoices:

• Add custom transaction numbers to sales forms in QuickBooks Online
• Customize invoices, estimates, and sales receipts in QuickBooks Online

Once done, check out this article to learn how to handle received payments: Record invoice payments in QuickBooks Online.

Keep in touch if you need any more assistance with changing your invoice numbers, or if there's something else I can do for you relating to QuickBooks. I'm happy to assist.