You can access watched issues by clicking the 
icon (Watch) in the global navigation bar.
When one of your watched issues has been updated, the icon in the global navigation bar will show a small green circle next to it.
You can add a personal note to each of your watched issues. Click the icon in the global navigation bar and hover over an issue. A text field will appear when you click "Add a note.” After adding text, click the "Save" button so that the note is added.
For more information about Watching issues, please read this.