Login to linux box which is in cust domian and run the following command:

for an example, I am connected to one of Linux box in XYZ DC.

$smbpasswd -r <domain name or AD server ip> -U <username>

Example:
alatheef@xyzxxxxdb0xs ~$ /usr/bin/smbpasswd -r 10.128.12.23 -U alatheef
Old SMB password:<put your old domain password>
New SMB password: <put your new domain password>
Retype new SMB password:<retype your new domain password>
Password changed for user alatheef