Elias here with Shopify Support. I'd be happy to help you with this!
You can replace the PayPal account in your Billing settings, which is accessible directly from the admin. The steps are the same as updating your billing information for a credit card on file. However, for other community members reading this thread, it's worth mentioning that the PayPal payment method for the subscription fees is only available for certain countries at this time.
1. Navigate to the Billing settings (Settings > Billing).
2. In the Payment methods, locate your PayPal account (or credit card).
3. Click the '...' icon next to it, and then click Replace.
I hope that helps! Let me know if this is what you're looking for?
Thanks for the follow-up!
Just to clarify, were you using a credit card or a debit card?
As mentioned on our guide, Payment methods for your Shopify bills - You can add a credit card to pay for your Shopify subscription. You can also use PayPal if that's applicable in your country. However, I'm afraid debit cards isn't an option for paying the subscription invoice.
Are you not looking to update the PayPal account anymore? Or, do you have a credit card you can try with?