Short answer

Open that week's occurrence of the routine from the Routines list, swap the assignees, and when you click Update Routine choose Update this routine ONLY. The cover applies to that week alone; every future occurrence stays with the original person. If you pick Apply to the [frequency] series from [date] instead, you'll have handed the round over permanently.

Detail

Each occurrence of a routine is its own row in the Routines list — the same round appears once for this Friday, once for next Friday, and so on. That's what makes single-week cover possible: you're editing one occurrence, not the template.

The flow:

  1. Routines → find the occurrence for the week in question. Check the Due Date — it's easy to open next week's by mistake.
  2. Open it, either with the pencil icon (side drawer) or by double-clicking the row (full screen). They behave identically.
  3. In the Related Tasks grid, remove the absent person from the Assignees column and add whoever is covering.
  4. If the whole round changes hands for the week, set row one and then use Bulk apply to all tasks (the copy icon at the end of row one) to push the assignees to every other row.
  5. Click Update Routine and choose Update this routine ONLY.

Reopen next week's occurrence to confirm — it should still show the original assignees.

For a permanent handover the flow is identical except for the last step: choose Apply to the [frequency] series from [date]. That applies the change to the occurrence you're on and every one after it, leaving earlier weeks alone.

Watch-outs

  • The scope prompt is where the mistakes happen. "Update this routine ONLY" and "Apply to the … series" look similar and sit next to each other. Read it before clicking Update — nearly every routine-editing complaint traces back to this one choice.
  • Check the Due Date first. If you're on a future occurrence and choose the series option, everything between now and that date keeps the old assignee. That's occasionally what you want (a handover starting next month) but usually isn't.
  • Getting it wrong is recoverable. Reopen the routine, make the change again, and pick the other option. Nothing is lost.
  • You can assign more than one person. If you're not sure who'll pick a task up, assign both and let sort by nearest and hide completed resolve it in the field.
  • Don't delete and rebuild for a week's cover. Deleting subtasks to "clear" a round is far more destructive than a scoped assignee change, and it asks its own this-instance-vs-all-future question.