How to ensure only my router is used

[G3RIR]

Hello,
I have a TENDA wireless USB tiny dongle. How do ensure that I connect only to my router? My router is by far the strogest signal that the TENDA can see but it insists on connecting to some BT open router nearby when I boot up. The BT router signal is showing very low but of course it is open whereas my router requires a passowrd

 

[Emerald]

remove it from the list of saved wireless networks on your computer