Your firmness and stability are assets in any office, but when facing a prospective employer, tone it down. Strive to be conciliatory and open to other opinions and ways of doing things.
Say things that convey you are confident and capable but willing to take on whatever your team needs.
"I embrace challenges and love to pitch in wherever possible" is a statement sure to put interviewers at ease. So does asserting your ability to thrive on deadline pressure and multitasking, and that you love leaving work each day with a satisfied sense of achievement.