Naturally, they get edgy when they interview someone who changes jobs every 18 months. The best answer is an honest one that hopefully hits the right chords. Some valid responses include moving on because you weren t working to your potential, the projects weren t challenging enough, you weren t motivated, or a change in command reduced your job function. Those are all answers an employer can understand. On the other hand, saying you left because you hated your boss or coworkers won t score points.
Employers don t want people who can t get along with others, especially if teamwork is required.
I d give careful thought to how you answer that question next time.