Hi.
I’m not sure exactly. Read this discussion: https://forums.raspberrypi.com/viewtopic.php?t=266724
I think you need to remove the SD card from your Raspberry Pi and insert it into your computer.
Then, you need to navigate to the wpa_supplicant.conf file: https://raspberrypi.stackexchange.com/questions/101261/where-is-the-wpa-supplicant-file

And insert the new credentials: https://forums.raspberrypi.com/viewtopic.php?t=235886

I hope this helps.
Regards,
Rui

Many thanks, sounds great, I will try it …  I love your courses! 

That’s great.
Thanks for supporting our work.
Regards,
Sara