This question already has an answer here:
Leaving company because I don't think the way they solved things was professional, ranging from how they dealt with clients to how certain in office issues were solved. My boss and colleagues were great but I wasn't happy with the rest. That's of course not the only reason why I'm leaving.
It was my first internship and they wanted me to continue working, but I've decided not to.
Next time I'm in an interview, in case this comes up, should I mention this? Should I go into detail as to why I've left the company? I don't want it to seem as if I had no reason and I do think want to go lengths lying as to why I've left it.
EDIT: What exactly should I say when asked why I left it? I feel anything I say I should be able to back up and also they will probably call the company to check out. I should graduate in 3 years.