Hi, I need your advice understanding and managing my credits.

My FICO® score: 620
Oldest account was opened 3 Years
Accounts carrying a balance: 9 accounts

I never missed payment, i usually pay all balances at the end of each month, my mistake that i learnt fron my friend was to use the credit card a lot instead of debit card and then pay it all each month. But learning my FICO credit report, i was utilizing 70% of my balance which affect it negatively.

Here is my 9 accounts:

Installment loans: $42,561 (Auto Financing)

Company: Ally Open Date: 10/2012 Balance: $21,483
Company: Fmcc Open Date: 10/2012 Balance: $21,078

Revolving: $16,483

Bk Of America Reward Open Date: 08/2009 Credit Limit: $3,000 Reward
Paypal Extra MasterCard Open Date: 03/2010 Credit Limit: $5,500 Reward
Cap One Platinum MasterCard Open Date: 05/2010 Credit Limit: $1,500 No Reward
Chase Freedom Open Date: 12/2011 Credit Limit: $4,000 Reward
Citi Forward Open Date: 01/2012 Credit Limit: $6,500 No Reward
Amex Gold Charge Card Open Date: 08/2012 Open Account Reward

BestBuy Credit Card: Open Date: 09/2012 Credit Limit: $2,500

It become too much to keep up with all the cards, using them all to ratio of 70% which caused my Fico score to drop for 760 to 620 in a year.

Do you suggest for me to close any account? especially the Capital One as there is no reward and the limit is small.

Should I close the Amex charge card and change it to Amex blue credit card?

Any advice how to manage this cards?

For the 2 auto loan installment, what's the best to handle it? I have money to pay 50% of the 2 loans but some people told me it is better to only pay the monthly installment in 2 years to help in credit report. (the 2 loans are 0 interest for 3 years)

Thanks guys for your help.