Timezone: open Agent Settings, then Agent Timezone, and pick yours. Until you do, the agent uses System Default (UTC). The timezone applies to greetings, business hours, scheduled tasks and voice-call preparation, and saving restarts the agent.
In the Custom Skills tab:
Built-in scheduled tasks: change the schedule, or turn them on or off. Their instructions come from the integration, so to change what they do, edit the related preference.
Your own tasks: add one with its own instructions and schedule, and delete it any time. Built-in tasks can't be deleted, only turned off.
Undoing an edit: a task's version history lets you go back to an earlier version, or to a built-in task's original setup.
Every run uses credits (see agent pricing). Details: managing scheduled tasks.