EDIT On 8/23/16 @ 5:00 PM PDT: Michael, there are two ways to solve your issue. I have written both methods below, the easy way and the technical way. 

Easy Way of Adding Default Terms & Conditions to Purchase Orders – Odoo Online Version 9 SaaS 11

Activate Developer Mode in Odoo Online:

1. Click on your name in the top right corner

2. A dropdown list will appear, click on About

3. Click Activate the developer mode link on the bottom right of the About prompt

4. You will notice a lady bug icon on the top banner to the left of your Discuss inbox icon

 Adding Default Terms & Condition for Purchase Orders the easy way:

1. Once in developer mode, click on the Purchases app in your database’s homepage

2. Click on Purchase in the top banner, and a drop down list will appear

3. Select Purchase Orders

4. Click CREATE  under the Purchase Orders title, and then a create new RFQ window appears

5. Click on the bottom left text box and write the Terms & Conditions you would like to save as a default

6. While having your cursor still in the text box click the lady bug developer icon in the top right, a drop down list will appear

7. Select Set Defaults  and a Set Default prompt will appear

8. Under the default drop down list, select the Terms & Conditions you just wrote

9. You can leave the condition field blank, however, you have the option to set different Terms & Conditions based upon the vendor you select

10. Click on All users to make sure your default Terms & Conditions apply to all of your database's users

11. Click on Save Default

12. Now every time you create a RFQ/Purchase Order, it will automatically populate
    
    

Technical Way of Adding Default Terms & Conditions to Purchase Orders – Odoo Online Version 9 SaaS 11

I must caution you that changing the reports architecture incorrectly (i.e. if your HTML code is incorrect), you can break the functionality of printing and sending your RFQ/Purchase Orders. So I only recommend you to do this if you are experienced writing HTML.

Activate Developer Mode in Odoo Online:

1. Click on your name in the top right corner

2. A dropdown list will appear, click on About

3. Click Activate the developer mode link on the bottom right of the About prompt

4. You will notice a lady bug icon on the top banner to the left of your Discuss inbox icon

Adding Default Terms & Condition for Purchase Orders the technical way:

1. Once in developer mode, click on the Settings icon in your database’s homepage

2. Click Technical on the top banner, a drop down list will appear

3. Scroll down through the list and click on Reports, a list of reports appears

4. Click on the Purchase Order item name in the list

5. In the middle of the window, click on Search associated QWeb views

6. Click on report_purchaseorder_document, and you will find the reports architecture.

7. Click on EDIT and above the o.notes field, insert your Terms & Conditions (written in HTML)

8. Now when you print a Purchase Order, you will see your Terms & Conditions.

Please let me know if this helps!