In your situation, since you passed one subject through the compartment exam and now want to improve all five subjects in 2025, but the application is only showing one subject available for improvement, you should consider the following steps:

1. Check the Rules for Improvement Exams: Most boards, including CBSE, allow candidates to improve their performance in one or more subjects. However, the rules may vary depending on whether you appeared through a compartment exam. If the system is only showing one subject, it might be due to restrictions on how many subjects can be improved after a compartment exam.

2. Contact the Board: Reach out to the examination board’s helpline or your school administration to clarify the rules about improvement after a compartment exam. They will guide you if any specific provisions apply to your case and how to proceed with multiple subject improvement applications.

3. Update Application Details: If your situation qualifies for improvement in all five subjects, the board may require manual corrections to the application. Request an update to your application from the board through official communication channels or email.

4. Submit a Request in Writing: If contacting the board doesn't resolve the issue, submit a written request along with any supporting documents (like your previous marksheets and compartment pass certificate) explaining your situation.

By following these steps, you should be able to clarify the situation and ensure your application reflects your intention to improve in all subjects.

Best Wishes. Good Luck!