Troubleshooting Issues with Making Changes in WordPress: Theme Modification

I’m facing an issue with making changes to my WordPress website. Whenever I attempt to modify the theme settings or update plugins, the changes don’t seem to take effect. I’ve tried clearing the cache, disabling caching plugins, and even switching to a default theme, but the problem persists. Additionally, when I try to upload new media files, they don’t appear in the media library. This issue is hindering my ability to update and maintain my website effectively. Any assistance in resolving this matter would be greatly appreciated.