SQL query is changing all names?

So i am trying to change a particular name, only the query is changing all the names.

UPDATE Team
SET Naam = 'besties'
FROM Team AS T 
INNER JOIN Gebruiker AS G ON T.GebruikerID = G.Id
WHERE (G.Gebruikersnaam = 'toppers')

The table "Team" looks like this:

The table "Gebruiker" looks like this

As you can see in both rows the Name is "besties", the idea is to change the Name only at one row.

In row 1 the Name was first "toppers"

>Solution :

I’m not sure about the syntax you’re currently using, but I would write it like this. I think this more clearly conveys that you’re only updating Team, and to be exact, only the Team of any of the Gebruikers named ‘toppers’.

Instead of in you could use =, if it’s guaranteed that Gebruikersnaam is unique.

UPDATE Team T
SET T.Naam = 'besties'
WHERE
  T.GebruikerID in 
  ( SELECT G.Id 
    FROM Gebruikers G 
    WHERE G.Gebruikersnaam = 'toppers'
  )