If you wish to change the way error messages are shown, you have to implement these settings in the configuration file:
Example:
If an error occurs, the user will see the error message like a table, and error fields will be highlighted by a red border and yellow background.
You can suppress text about which fields were not filled correctly, and show your custom text instead of it using short_error_message in the config.php file
Example:
If an error appears, the user will see only the line: Please, fill in highlighted fields with correct information.
Remember to put the <!-- FPP_ERROR --> tag at the point in the page where you'd like to display the error messages.