WordPress Filesystem permissions fail to be writable, even changed wp-content folder to 755 or 777

Hi Riku, thanks so much at first. I just set "wp-content" this whole folder to 755. All files inside, I didn't do anything for that. Did you mean, I should also set all of them individually to 755?

Cheers Shiyu

If you change the permissions on the "wp-content" folder, you can still create files. However, individual files should not be able to be deleted or edited without editing the permissions on the individual files.

Thanks so much. While, the problem I am facing is that I could not create any files or folders via WordPress dashboard when I wanted to downlaod any theme or upload img to there. Even my "wp-content" is 755 for now.