How to secure my router password

[henry200956]

My problem is if someone uses my laptop computer which is on wireless to the modem-router, they can easily find my router password by highlighting my network connection in the task bar then by viewing the properties, then click the box to view security key all in about 10 seconds they can then go home and if in range use my router connection for free
I know how to hide the connection icon but thats as easy to find as to hide

 

[V_R]

IT shouldn't actually show the key, just a bunch of asterisks.