If you're experiencing an issue where the PHP Selector in ISPManager isn't changing PHP options as expected, here are some steps you can take to troubleshoot and potentially resolve the issue:

1. Check PHP Versions: Ensure that you have multiple PHP versions installed on your server, and that the PHP Selector is configured to select from these different versions.

2. Confirm PHP Selector is Enabled: Verify that the PHP Selector feature is enabled in your ISPManager settings. It should be enabled to allow users to select different PHP versions and options.

3. Check User Permissions: Ensure that the user trying to change PHP options via PHP Selector has the necessary permissions. They should have the right to modify PHP settings for their domains or accounts.

4. Validate Configuration Files: Check the configuration files for your PHP versions. Sometimes, incorrect settings in these files can cause issues. Make sure that the correct PHP options are set in the configuration files for the selected PHP version.

5. Restart Web Server: After changing PHP options, you may need to restart your web server (e.g., Apache or Nginx) for the changes to take effect. Use the appropriate command for your web server, such as systemctl restart apache2 or systemctl restart nginx.

6. Clear Cache: Sometimes, browser cache or server-side caching can cause issues with changes not immediately reflecting. Clear your browser cache and any server-side caching mechanisms that may be in place.

7. Check for Error Messages: Look for any error messages or warnings in the ISPManager logs or PHP error logs. These logs can provide clues about what might be causing the issue.

8. Test with a Different PHP Version: Try changing PHP options for a different PHP version to see if the problem is specific to one version. This can help isolate the issue.

9. ISPManager Updates: Ensure that you are using the latest version of ISPManager. Sometimes, updates can resolve bugs or compatibility issues.

10. Contact ISPManager Support: If the issue persists and you can't identify the problem, consider reaching out to ISPManager support or their community forums for assistance. They may have specific insights into the issue.

11. Review Documentation: Check ISPManager's official documentation or knowledge base for any specific troubleshooting steps related to PHP Selector and PHP options.

12. Backup and Restore: As a last resort, if the issue can't be resolved, you might need to back up your current ISPManager configuration, reinstall it, and then restore your settings. This should be done with caution and as a last resort.

Remember to proceed with caution when making changes to your hosting environment, especially if it involves restarting services or modifying configuration files. Always keep backups of your data and configurations before making significant changes.