How to change the lookup dialogue's record display format. Whenever I click on a lookup field to display the list of records, it only displays me "Recently Viewed" records, however I need to view all the records at the time I click on lookup icon. Can I also add other columns in my lookup results (as in lookup dialogue box, only Names of records are displayed, what If I want to add another field/column as well here). I checked "Search Settings" but it didn't solved my problem. Please help.
if you want to add other column in lookup dialog then open any sobject detail page go to search layout there is Lookup Dialogs option edit Lookup Dialogs and add column which you want to display . i show you one example check
Why does Lookup Search without any search string not return all records? Resolution If the user does not enter a search string before clicking the Lookup Search button, it doesn't return all but just the 20 most recent items the user has clicked on. This is because this display will be a dynamic entry if we do so on the salesforce search engine, therefore it will make the display based on each organizations private settings. This will cause a delay on our servers because of so many individual queries. This means to ensure the top performance on speed and data retrieval we have decided to leave the default to the most recent ones. So in short, a full list of all records for an object is not available in Lookups for performance reasons.
Setup>Customize>Search>Search Settings contains a "Use Recently Viewed User Records for Blank and Auto-Complete Lookups" which can be disabled. This would probably fix your problem, which means that article is probably outdated... salesforce not support Showing all the available records in Lookup Dialogue by default instead the recently viewed records. u check here and vote for idea https://success.salesforce.com/ideaView?id=08730000000YfjZAAS