¡Hola!
Try this :
- turn the Macbook OFF
-
reset the NVRAM
- go to System preferences / Startup Disk, select you main partition as startup disk (this was reseted by the nvram reset)
- turn the Macbook's wifi OFF
- go to System Preferences / Network / Wifi / Advanced,
delete the two networks from the network list
- go to Applications / Utilities / Keychains, type in "airport" in the search field, make sure that no entry exists for the two deleted networks. If you find some, delete them
- turn the wifi ON, select the first network, enter its password
- now select network two, enter its password