There are no cells in Access.  In Access they are fields.
Where are you trying to do this?  In a form?  It makes a difference.

Databases do not have cells. You can use an Update query to fill a number of
rows with the same data within a set of parameters. Usually, the same data
in every row is an indication of poor design, but there are some instances
where you might want to like the same City, State, and zip in multiple rows.
For that, we normally set a default value for the field, which can be
changed if the data is different.

If you are working in a datasheet form (not the table ... do not work
directly in tables) you can use Ctrl+" to copy the data in the row directly
above to the field you are entering data. You can use code to set the
default value to the value just entered:

Sub txtMyField_AfterUpdate()
   txtMyField.DefaultValue = """" & txtMyField & """"
End Sub

That's 4 double quotes on each side.