Can I stop authors from changing the font in their post?

You can deactivate the buttons on tinymce and html-editor, but the user can than also create html-tags. Then is is also possible you filter the_content and replace the font-tags with empty fields.

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)