To edit a Dashboard, you will first need to click on the Cog highlighted below, then click on Edit. Note the Edit option will not be visible if you are not the owner of the dashboard.
Once you click on Edit above the dashboard will be on Edit mode together will all the linked Widgets, displaying a Cog as highlighted below:
Clicking on the Cog displayed on the Widgets provides you with the ability to Edit that particular widget e.g. The Ideas Widget.
The above dialog allows you to select the criteria that should be used when loading the dashboard, e.g. you can use the Status filter to select the Ideas you would like to see. e.g Active, Cancelled, On Hold etc. When you have made the required selection remember to Save the Widget and the Dashboard.
If there are no selection criteria the Widget will display all data you have access to.