You've hit on a very common problem that's less about the steps and more about the platform's configuration quirks. The official steps are indeed simple: navigate to the main Issues module, ensure you're in a list view (not a dashboard widget), select the checkboxes for the issues you want to merge, and then the "Merge" action should appear in the toolbar.
However, based on the follow-up discussion, your issue is almost certainly environmental. There are three typical failure points that explain why you can't see it.
First, and most likely, is a permission mismatch. The ability to merge issues is often gated behind an "Issue Manager" or "Power User" role. You might have edit permissions but not the specific "Consolidate" or "Merge" right. You'll need an admin to verify your role's action permissions.
Second, you could be in a read-only view. As others noted, a pinned dashboard view looks identical to the functional module but lacks action buttons. You must navigate directly to the module via the main menu.
Third, the button could be hidden in a toolbar overflow menu (a tiny downward arrow on the toolbar's far right), especially if your admin has customized the view or if the system's algorithm has demoted the "Merge" action due to low usage stats.
A hard refresh (Ctrl+F5) or even a full logout/login after a permission change is also a necessary troubleshooting step, as the UI caches your available actions.