I'm so sorry. I went years thinking paying for eBay Shipping from my bank account was the only way to do it. Then it took me several tries before was able to remove the preauthorization for eBay Shipping to deduct from my bank account and default to the CIP. I feel your frustration.
Here are some ideas?
1. Log into your PayPal account.
2. On the top right, click the Settings widget.
3. On the top nav bar, click Payments.
4. Click Manage pre-approved payments.
5. Under Automatic Payments, you should see eBay Inc Shipping. If so, click it.
6. Details for eBay Inc Shipping should expand to the right. Next to Payment method, you should see an Edit icon -- click it, select your CIP, and Save.
If all that doesn't work next time, go back into PayPal>Settings>Payments>Manage pre-approved payments>eBay Inc Shipping, and click Cancel. The next time you print a shipping label, there should be a Pay and Print button and a check box asking if you want to pay with your PayPal balance (don't check this; and it's better to just withdraw your PayPal balance before printing a shipping label because PayPal will use funds from your balance before your bank or card). Click Pay and Print without checking the box, and you might be asked to log into PayPal and should have the option of choosing your method of payment, including the CIP.
See if this works, and if not, I can circle back and help with canceling your existing eBay Inc Shipping preapproval and setting up a new one.
P.S. New avatar with your sisters!