Note: if you do not have a previous version of FrontlineSMS v2 on your computer then you can download and install directly.
Before you can upgrade to use the latest version 2.6.1, it is important that you remove any old FrontlineSMS application version from your Applications folder. All of your data will be retained, it is simply the application itself, and not the data, that you are refreshing.
Step 1: To find where the app is stored, Use 'Spotlight' (normally a magnifying glass icon in the top-right of all screens) to search for "FrontlineSMS". Once matched, click 'Show All' to view the app itself in its folder location (clicking on the result itself will run the app).
Step 2: Delete the 'FrontlineSMS' application. You can use cmd+Delete for this, or right-click and 'Move to trash'. This will permanently move the app to the Trash. All your data will be retained as it is stored in a separate directory.
You need to ensure that FrontlineSMS is not running while you delete it.
Step 3: Download and run the FrontlineSMS 2.6.1 installer. This will install the latest version and upgrade your data which should all be intact.