Thanks for posting your query to Microsoft forum. I will certainly help you with this.
You might face this issue if your computer is not connected to internet. If it does not have the internet connection it will take the old password however, if you have the internet connection check the following steps.
- Make sure that you have a secure internet connection to that PC/Laptop may it be wired or WiFi or even Hotspot.
- Make sure to connect using the option under your network settings in the bottom left hand corner of your Sign-in screen.
- Check if your password is correct and then enter it carefully.
- Once you are connected then only can you type in the new password you have changed.
- Make sure that your Caps Lock is not On.
If the issue persists, try to reset you password online again
here, and use the new password now.