How do you convince a negative mind boss ?
Make him think it's his idea.
Hope this helps - http://letsgrowleaders.com/2013/11/01/how-to-persuade-boss/
From what it sounds like,your going to need to have courage to state your opinion.Think it out what or why you need to be heard. Some people like your boos won,t change unless you can persuade him,how you feel.
Be polite, practical and afflable when communicating with him. Smile.
anonymously leave the book ''Positive Mental Attitude'" on their desk