When created Watch, it is applied for all devices of that family. How to apply only for selected models.
Spectrum 20.X,21.X and 22.X
Active By Default is selected when creating Watch.
When creating Watch, in Properties tab Uncheck "Active By Default" option.
Below screenshot is FYR:
Active By Default
Specifies whether the watch is active by default for all models that inherit the watch. If this option is not set, activate the watch manually for the desired models.
After successfully creating the watch, navigate to selected device model - Component detail - Thresholds and Watch SubView - Watch - Select the watch - Activate it.
This way Watch will apply on model we activated it. For other models it will be listed but will be in Inactive State.
https://techdocs.broadcom.com/us/en/ca-enterprise-software/it-operations-management/spectrum/22-2/managing-network/watches/create-and-edit-a-watch.html