Go to https://www.atlassian.com/software/jira 

Enter the issue number you want to add a watcher to in the search bar and click the "Search" button.

Click the "More" dropdown menu and select "Manage Watchers".

Enter the username of the person you want to add as a watcher in the "Add Watchers" field and click the "Add" button.

atlassian.com

If you are a project manager or team lead, you may want to add a watcher to an issue in Jira to keep track of progress and ensure that the issue is being addressed in a timely manner. By adding a watcher, you can be notified of any changes or updates to the issue, allowing you to stay on top of the issue and ensure that it is being addressed properly. Additionally, adding a watcher can help to ensure that all stakeholders are kept in the loop and are aware of any changes or updates to the issue.

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