Your credit score is based on your use of Debt.
From wikipedia:
- 35% of your Credit Score is devoted to Debt Payment History.
- 30% of your Credit Score is based on Utilization (basically, the amount of unused credit available).
- 15% of your Credit Score is impacted by your Credit History.
- 10% of your Credit Score is based on Inquiries for new Debt.
- 10% of your Credit Score is determined by Types of Debt.
Opening and closing bank accounts, buying or selling cars without debt, or even buying or selling houses without debt won't affect your credit score.