Note: Setting all adverts in a group to a higher or lower weight will defeat the system as all have an equal chance of being shown.
Note that the weight override is a minimum weight. If you set it to 4 no ads with a lower weight will show for that location.
You can overrule set weights using shortcodes and PHP. This allows you to set all kinds of weights for each ad but set a random minimum level of weight for a certain location.
Shortcodes can be used in Posts, Pages and certain widgets.
[adrotate group="2" weight="6"]
PHP goes in your theme files. Typically index.php, single.php or page.php.
Groups (group 12, no fallback, weight 8):
echo adrotate_group(12, 0, 8);
Groups (group 2, fallback group 2, weight 4):
echo adrotate_group(2, 2, 4);