Welcome to the Apple Community.
Contact Apple through iTunes Store Support, and explain that you have forgotten your 3 security questions, that you can reset your password, but doing so doesn't reset your security questions.
Explain that after resetting your password, you are still asked for the answers you have forgotten, before you can gain access to My Apple ID > Manage your account > Password & security, which is where you need to be to change your answers.
Remember, support will receive hundreds, if not thousands of requests per day, some from people trying it on, others with little explanation and others that are written extremely poorly. Take the time to explain your situation properly, be precise and concise, brief but comprehensive.