...how do we change our account password?

D&D Beyond doesn't have an individual login. It uses Twitch, Google, Discord accounts. If you normally login using your Twitch account, then you will need to head over to Twitch and change your password there. If you normally use your Google account, then go to Google and change it there, etc.

Sweet, so I'm an idiot still, but I was on the right track. Thank you for your help, kind traveler.

would this automatically log you out of all devices? come people i no longer have contact with have access to my account so i want it off their devices

No, or at least not automatically, but they may have options to manually remove devices authorised, which would kick them off. Twitch, Discord and Google do have have this. 

For Twitch click your profile icon, go to settings and then the Security and Privacy tab. There is an option to "sign out everywhere".

For Google, head to google.com and click your profile icon then the 'manage your account' button. On the left click 'security' and then scroll down to the 'devices' section and click the link below the list 'manage all devices'. From there you can select a device and click 'sign out' to force that device to be signed out. You will need to this for each device.

For Discord click your profile pic and then user settings, (if your on the app clicking your icon goes to user settings automatically). The click Devices and at the bottom is "log out all known devices". 

thanks, i went to change my password on my google account and noticed there was an option to remove the devices there, i sent a support ticket to WOTC also and they replied saying my account was signed out of all devices but apparently that was a lie