The name of the topic can be changed both in the extension and the Dashboard.
Changing the topic name from the extension
Find the topic you want the name changed for, click on the pen (or double-click on the name once the topic is opened), and start editing.
Once you're done, click on the checkmark to save the changes.
Changing the topic name from the Dashboard
Find the topic you want the name changed for, click to open it and then simply click on the topic name to start editing it.
It will automatically be saved.