->All stored credentials (central list)
Main menu – Credentials and Passwords (or Credentials / Credentials Manager). This shows every credential record you’ve added and lets you edit/delete them.

->Which credential a backup job uses for guest-OS / application-aware processing
Backup & Replication- Job- right-click the job- Edit- Guest Processing (or Guest OS credentials / Application-aware processing). There you’ll see if the job uses the Default credential or a specific credential record for each guest/VM.

->Credentials used by infrastructure components (to deploy/communicate with hosts, proxies, repositories)
Backup Infrastructure – Managed Servers, Backup Proxies or Backup Repositories – select the server/proxy/repository – Properties. The credentials used to connect to that managed server are shown there.

->Veeam Agent / Protection groups
If you use agent jobs or protection groups: Protection Groups – select the protection group – Properties – Credentials (Master account / per-computer credentials).