I am trying to configure a viewer group on my tempo report whenever i refresh th

This is because in environment A the viewers group is "Group1" and in environment B is "Group2", when you exported it from environment A and imported into B the viewers role got merged, which is the default behavior in Appian, but only one group is allowed.

This shouldn't be a problem in newer versions (7.7+ where the new Records Designer allows multiple groups in the security)

In the meantime what I suggest is to export the record (nothing else) and attach it here so I can remove the extra group.

Just let me know the UUID of the group you want to preserve as the viewers

Are you going to change it manual in xml file of the build ?

Correct

Best way to handle this is to remove Viewer group from target system before the import from the respective reports.

Yes that works too and should be the approach used when not working with Appian Support.