To change metrics being collected, you have to use the "Collection Settings" (listed above) to enable or disable the VMware object being collected (Cluster, VM and Core Metrics, etc.). To figure out what you need enabled, use the following chart to view the Metric Class:
Then, use the link https://helpcenter.veeam.com/docs/mp/vmware_reference/metric_definitions.html?ver=80U6 to find the remaining entities you want to collect on; in my example I will use snapshot age. To change snapshot age collection, it is listed under VMStats using the previous link. Then using the Metric Class Chart, VMStats is listed under "Virtual Machine Core Metrics" which must be check boxed in order to collect on. The issue is that VMStats alone has 59 other objects that are going to be collected on that may or may not be desirable.
Once you have the metric you want to collect on (snapshot age), you can change what is collected based on the Rules in SCOM. If you go to Ops Manager --> Authoring tab --> Management Pack Objects --> Rules --> VMGUEST.Collect.snapshotAge (for my example) --> Enable through Overrides to verify it is being collected on the group you want. If you do not see VMGUEST.Collect or any other nWorks rule listed, you may need to change the Scope to "Look for" nwork "View all targets" to see the full list.
Then once you have the snapshot rule set to how you want it, you can then disable other rules being used by VMStats through Overrides within the same collection group; listed as "vmguest.collect." for this case. Once done in this way, you can control what you collect on a more granular level to see only the information you want to see.