The text of the war diaries is designed to be searchable on the basis of any keyword or search term, whether a place name, personal name or anything else.
The Adobe Reader's "Open full Reader search ..." option lists the instances where the search term appears in the text together with some context and allows you to go straight to the place where it occurs. To access this facility, right click on the text and select "Find" (or Ctl+F). In the drop-down list on the Find button at the top right-hand corner of the screen, select "Open full Reader search ..." (or Shift+Ctl+F) and follow the instructions. For Macs, the default pdf viewer is Preview, which has a search facility at the top right-hand corner and displays search results on the left-hand side of the page.
The purpose of the "All" button alongside the monthly buttons under each unit is to enable the entire period to be searched at the same time and the "Search All" button allows a search to be made of all the battalions' diaries at the same time.
It is advisable to be as creative as possible with search terms as the spelling of place names or personal names appearing in the diaries is not always correct or consistent. Searching on only part of the name, for instance, may yield better results.