If at all possible, we always recommend automatic tracking of a customer's subscription status. But, you may very well find times when you simply need manually adjust a customer's MRR or trial/churn status.
To do so, either select the accounts you'd like to edit in the Accounts view or navigate to the account's dashboard. Click the dollar icon $ to move the account to a different stage in the subscription lifecycle or change their subscription details like their MRR.