I suggest trying another browser, Internet Explorer is old and may not be fully compatible, I also suggest you to have a look at the Microsoft exam reschedule policy over here:
https://learn.microsoft.com/en-us/learn/certifications/exam-reschedule-and-cancellation-policy
Also note that Microsoft Certification / Exams is currently not supported in the Q&A forums, the supported products are listed over here https://learn.microsoft.com/en-us/answers/products (more to be added later on).
You can ask the experts in the dedicated Microsoft Certification - Exams - Exam Registration and Scheduling forum over here:
https://trainingsupport.microsoft.com/en-us/mcp/forum/mcp_exams-mcp_exam
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(If the reply was helpful please don't forget to upvote and/or accept as answer, thank you)
Best regards,
Leon