Thank you for your post and welcome to the Community Forum!
In general, there may be multiple reasons why you cannot pay with your account. For example, your funding source may not be active and in that case, please reach out to the issuer of the funding source that you chose. Otherwise, it may be that your account has been limited and in that case, simply complete the steps in your Resolution Centre to resolve the issue. Also, it may be that our system is preventing you from paying with your account for security reasons. In this case, we would not be able to manually change the security settings, but you can try clearing your cache and cookies, deleting your browser history and waiting for 48 hours without accessing your account to let the system reset. This may help you solve the issue!