If you have negative information on your credit report, it will remain there for 7-10 years. This helps lenders and others get a better picture of your credit history. However, while you may not be able to change information from the past, you can demonstrate good credit management moving forward by paying your bills on time and as agreed. As you build a positive credit history, over time, your credit scores will likely improve.
Reducing your balances on credit cards and other revolving credit accounts is likely the better option to improve your credit utilization rate, and, subsequently, your credit scores. Consistently making on-time payments against your debt will also help you build a positive credit history, which can have additional benefits for your credit history and, by extension, your credit scores, too.