I think you should just write that u want to try something knew and u didn't really like the enviroment u worked at your last job.

i'm QUITTING my current job right now because:
1. i think my manager is racist towards asians (my race)
2. i haven't gotten an raise for months, too scared to ask for raise ..because he's intimidating
3. he picks on me all the time, telling me that i'm doing this and that wrong when it was just a 1 time MISTAKE
4. i'm always "on call", which ruins pretty much all my plans
5. i deserve way more then i'm getting right now since i work my ass off (fast food=really really busy)

i just want to work somewhere relaxing where i won't get as tired by the end of the day after i go home from work.. =\ i'm probably gonna go job hunting next month for a new job, hoping to get hired at a retail =)