There are 2 titles that will display in the tab for each page. The public name of the page will display first, then the Site Name defined in the page wrapper will be displayed, separated by a dash. For example:

Public name of the page (defined in the page) - Site Name (defined in the wrapper)

The Site Name is configured in the page wrapper associated with that page or event. To change what displays after the dash, go to:
  1. Navigate to Setup > select Page Wrapper Editor
  2. Search for the wrapper in question and click Manage Versions
  3. Click Copy for the Active version and click Edit for the new version
  4. Go to Step 2. Meta Tags
  5. The field under Site Title is where you can add the title for the pages