Recently, my Debit Mastercard had been compromised and I had to get a new one.....naturally this leads to me having to resubscribe here, and update my account detalis. How do I do this? I can't seem to find the page where I type all the new information in. 

Where has it been hidden?

https://www.dndbeyond.com/store/subscriptions/manage

Just scroll down to the bottom.

Quote from IamSposta >>

https://www.dndbeyond.com/store/subscriptions/manage

Just scroll down to the bottom.

I clicked on your link and kept getting that page with a clock-work Dragon standing over some tools telling me "Couldn't Collect Payment , blah blah blah blah, Customer Support... Cancel subscription. (in a another link.)

I don't want to do that.

Can you put up a screenshot showing me where to click to upgrade my account details?

Don't worry, I found it..... :)

Where exactly, I know I fixed this problem before by doing the same as you told me, but things seem different down here now?

Same link as above: (https://www.dndbeyond.com/store/subscriptions/manage)—

I'm truly sorry, I don't understand you. How did you get to that page? Did press the link for the Free Trial and in my case, it would be the Master tier?

This only takes me to the page where it says it could not collect my payment?

Unless you want me to click the link that says, Cancel Subscription. I won't be doing that because, I have roster of characters that I use on mine. It would be very hard for me to retreive those if lose my current subscription.

Please show what did you press to get to those pages...????

As your link always takes me to the Cannot Collect Payment screen described above.

I don’t k know what to tell you. I used the link I provided and then scrolled all the way to the bottom of the page.

It's okay now somebody showed me. I simply had to cancel my subscription and then resubscribe. I didn't want to do this thinking I might lose all my characters, but that never happened.