how can i change from customer X to customer Y but the nodes are in different groups?
referring a massive change not one by one
Nodes have several grouping characteristics that can be assigned to them. The primary one is "group" but you can also associate a node with a "customer" and/or a "business service". The membership of these groupings is independent of each other so devices A and B could be a member of group1, with device A being part of Customer "foo" and device B being part of Customer "Bar".
This page has all the details:
To edit devices in bulk you would probably be best to use :