Your library account used to be call Display or Renew Items checked Out to You. Your account is now called My Library Account. The link above will explain all the new features you now have with your library account.
Multi on a keyword browse screen indicates multiple locations and you will have to click record link to view the record to see the various locations.
Advance Keyword Searching you can search for words adjacent to each other. The order of words matters. Multiple words are searched together as one phrase. For different results, use and between words or phrases. You can also use operators in your search string. Use or to expand your search to include similar words or alternative spellings. Use and to narrow your search by demanding other words be included in the record. Use and not to exclude words. Use parentheses to group or words when using multiple operators.