Two different editors are available.
The Summary editor allows for most changes to the data
The GEDCOM editor provides a detailed view of the GEDCOM data. see GEDCOM Editor

The Summary editor, allows the GEDCOM database to be updated, and edited.
Double Click on a person, or family in the table to edit the GEDCOM

Summary Editor
(Click on the image to enlarge)

Use the Summary editing, for adding Facts, Media, Notes, Research Notes, Sources and TODO's
Summary editing, is usually all you need, and is more convenient.

View / Add Hash Tags   HashTags can be used in the table search.
View / Add Web links

Use +Event to add facts.
Click on the link, to edit the facts.
For the editor, values are not committed until    is pressed

Confirm Edit
(Click on the image to enlarge)

 The changes can be reviewed and backed out in GEDCOM ⟶ Session Log ...
 Move the windows around by dragging on the Title Bar.
If the title bar is not visible move the window by holding down Shift and drag on the background.
View the window manager using