Increase mysql limits

Hello!

I searched a lot before opening this topic and did not find the answer.

I need to change the mysql connection limit, max_user_connections and max_connections

Whenever I change the my.cnf I get the error in time to restart the mysql.

Please, where I have to change the settings so that work ??

Grateful!

Excuse my English, I'm from Brazil and I'm using Google Translate