If you want Add Custom “Sort By” Drop Down options In Magento visit thie page.
Step 1: Navigate to the app/design/frontend/base/default/template/catalogsearch/form.mini.phtml if you are using the default Magento and if you are using your custom template navigate to the app/design/frontend/base/default/template/catalogsearch/form.mini.phtml and search for the form.mini.phtml
Step 2: Now Open this file in your favourite editor.
Step 3: Now Search for the starting form tag.
Step 4: Add the code just below to the form tag
<input type="hidden" name="dir" value="desc" /> <input type="hidden" name="order" value="relevance" />
So whenever user will use the quick search, it will show the data by default sort by descending relevance.
Hope it helps and if you need the professional Magento Development we can help you, just Click on the Link and send me your requirements.
Please Like the Post on Facebook or Google+.