3column Layout turns to 2column Layout

[Herminegrang3r]

Hello,

we are using Drupal 6 together with YAML as theme for our site.

On most pages a 3 column-layout is used. What/where do i have to change in Drupal to switch to 2 column-layout if the user switches to the (extended) forum part ?

[hass]

I would use the base theme. It have dynamic side bar switching. This is perfectly as it's dynamic.