How to change column layout of search results page

You need to edit the following file:
/app/design/your_interface/your_theme/layout/catalogsearch.xml

Search for setTemplate. It’s located in 4 places in the page. (catalogsearch_result_index, catalogsearch_advanced_index, catalogsearch_advanced_result and catalogsearch_term_popular)

For example:

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<action method="setTemplate"><template>page/2columns-left.phtml</template></action>

Update the name of the template you wish to use in between the tags

After update:

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<action method="setTemplate"><template>page/newtemplate.phtml</template></action>

All Done!