IN: The balances on your installment accounts are too high in comparison to their credit limits.
An installment account is one with a fixed monthly payment for the life of the loan. Auto loans and student loans are common examples of installment loans. The outstanding balances on open installment accounts remain high compared to the original loan amounts. People who haven't paid down much of the original amount on installment loans are higher credit risks than people who have.
As monthly payments are made, a portion of the outstanding principal balance is reduced, benefitting your score. Whenever possible, further pay down balances on your installment loan accounts. Over time this will also have a positive impact on your score.