Change my database WordPress Prefix for better security

Hi this is probably a very simple task for anyone who has a good understanding of MySQL, php and working with Wordpress. I currently have 2 Wordpress blog sites up and running. However on both sites the database prefixes still use 'wp_', to add more security I want the database prefixes changed to something like 'wp_kl8494jdeJ' . I need both of my sites changed. I wont go into detail but I have tried changing the prefixes myself in and due to my inexperience wasn't sure if I did everything right. So I would rather have someone with professional experience do it. This job is easy money and should not take very long at all for someone who is good with wordpress and MySQL. $30 USD is what I will be paying. I must feel that you are trustworthy and competent to complete this as you will need to have access to my cpanel. Thank you.