I'm doing a manual install of wordpress & have already setup my MySQL database using the database wizard & nowhere in the database setup was there a way for me to pick my own table prefix. I previously installed wordpress using my hosts software installer & then used the plugin "WP Security Scan" & it warned me about the table prefix wp_ needing changed. I'm trying to set it up correctly the first time to prevent SQL injection attacks from being performed. I emailed my host & they said that wordpress sets it up on it's own I know it does wp_ How can I set it up correctly the 1st time during the manual install it's a pain to change once it's setup wrong.
You are making this harder than it has to be. If you don't have knowledge of customizing database tables, you really shouldn't be messing around with it. Just install Wordpress normally, and install a basic Secure Wordpress plug in afterwards. You are worried about problems that don't even exist from a scan designed to make you panic about everything. And making things hard on yourself for no reason. Have you ever had an SQL injection attack happen to you? Do you even know what it is? Do you know what else can happen? Locusts can attack your hosting company, clogging all of the fans of the servers, over heating them and take down all of their websites. Stop freaking yourself out and install the software normally. Secure your installation after you have it set up. I'm not saying not to take your site's security seriously, but you are so worried about everything under the sun that you can't even get it installed and get a website up. You can't stop every possible scenario before you even have a website to even worry about. Work with your host on security and stop freaking out about SQL attacks, databases, cache programs and everything else and just get the thing up first.
If you absolutely have to do it to feel secure, here is a support thread that discusses it: http://wordpress.org/support/topic/database-prefix-change And you only need to do a Google search if you need more articles and tutorials like this one: http://www.talkincode.com/changing-your-wordpress-database-prefix-91.html
If it is a new installation, then i would re-install, but if it is not you can change it manually. But don't forget to backup all the database first, before changing it.