Did you receive an error when updating your new card details?
If not, we can try some basic browser troubleshooting. Let's start by logging in to QuickBooks in a private window and update your card. While your computer stores copies of frequently accessed pages in its memory cache, private browser is a good place to start the troubleshooting. Since it doesn't store any cache. which may be the cause why you're unable to update your credit card information.
Then, try updating your billing information to reactivate your account.
Go to the Gear icon (⚙).
Select Account and Settings.
Click the Billing & Subscription tab.
Under Subscription status, click Subscribe Now on the right part.
I'm here to ensure that you'll be able to update your billing details successfully so you can resubscribe to your QuickBooks Online account.
I'd like to let you know that, when updating your billing info in QuickBooks Online, it can take up to 24 hours to activate your account. Since you're unable to proceed with resubscribing your account, I recommend contacting our Customer Care Team. They have the tools that can help you update and reactivate your subscription.
To add up, you can always scan through these links below that provide details about the different ways of updating your billing details in the system together with the accepted cards: