How can I add terms and conditions to quotes/invoices?

It's nice to see you here, @bensyapaintingpa,

I'll guide you through the process of attaching documents to your sales transactions. To attach files on invoices, use the Attachment feature in QuickBooks Online. Here's how to attach files in the Attachments page:

1. Go to the Gear icon and select Attachments.
2. Click the Attachments icon to open the files.
3. Hold the CTRL button on your keyboard and select the items to upload.
4. Once everything is selected, release the CTRL button and hit Open.
   

To attach documents on transactions:

1. Open any income or expense transactions in QBO.
2. At the bottom click the Attachments icon.
3. Do steps 3 and 4 from the instruction above.
   
4. Make sure to click the Attach to email option.
   

Get to know more about this Attachments feature by checking out this article: Attachments in QuickBooks Online

If you need further help with attachments or other QuickBooks topics, let me know in the comment. I'm always here to help you. Have a wonderful day!

@bensyapaintingpa 

Another option, explore this app to integrate with your QBO. When your customer accepts your quote, it will generate the invoice automatically.

https://get.practiceignition.com/quickbooks