New Macbook receive bad wifi signal

It may not be the WiFi signal, but something else.

Can you do following:

hold the Alt(option) key while clicking (and holding) the WiFi icon on the menubar when you see the list underneath let go of the Alt(option) key, the list should stay there, then make a screen grab of that list and post it here. Or make a picture with your phone, email the picture to yourself then post that picture here.

Lexiepex is right in suggesting that you gather some information about the WiFi signal strength and share it with us.

For a lot more information including some guidance in interpreting the numbers you get from the option (alt) menubar icon, you could read this rather lengthy support article: Use Wireless Diagnostics to help you resolve Wi-Fi issues on your Mac - Apple Support

These (below) are most of the Wireless Best Practices that come at the end of the diagnostic testing. The missing one is Configure Your Network to Use a Unique Network Name.

You didn't mention what sort of router you are using. That might be helpful information.

dick glendon

The warranty entitles you to complimentary phone support for the first 90 days of ownership.