Im not real familiar with yahoo's blog manager, but I know getting to phpmyadmin using their hosting package can be a bear so, edit your wp-config.php, correcting the changes you made:
WordPress address (URL)
WP_SITEURL, defined since WordPress Version 2.2, allows the WordPress address (URL) to be defined. The valued defined is the address where your WordPress core files reside. It should include the http:// part too. Do not put a slash "/" at the end. Setting this value in wp-config.php overrides the wp_options table value for siteurl and disables the WordPress address (URL) field in the Administration > Settings > General panel.
NOTE: It won't change the Database value though, and the url will revert to the old database value if this line is removed from wp-config.
If WordPress is installed into a directory called "wordpress" for the domain example.com, define WP_SITEURL like this:
Blog address (URL)
WP_HOME is another wp-config.php option added in WordPress Version 2.2. Similar to WP_SITEURL, WP_HOME overrides the wp_options table value for home but does not change it permanently. home is the address you want people to type in their browser to reach your WordPress blog. It should include the http:// part. Also, do not put a slash "/" at the end.
If you are using the technique described in Giving WordPress Its Own Directory then follow the example below. Remember, you will also be placing an index.php in your web-root directory if you use a setting like this.
Im assuming those are 2 settings that manager thing changes.