Change the template for the forum.

Hellow. My English Bad, use google translator. I have template. Example: [img]http://rgho.st/7dyFlZ2sK/thumb.png[/img] - photo1 I want change template for forum: I want this: [img]http://rgho.st/6Sxfh88Xl/thumb.png[/img] - photo2 How make it ? I try: Make new page, change template to "full width disable sidebar template" and set shortcode: And it work, like photo2 [img]http://meson.ad-l.ink/7HJlTZLzx/thumb.png[/img] site.ru/forum But, i go to - site.ru/forum/NewTopicTest/ and now get template like photo1 [img]http://polariton.ad-l.ink/8CTk484dr/thumb.png[/img] How make "full width disable sidebar template" for all forum?