Every contact, company or deal to follow up appears in the Follow-ups row at the top of the Agenda, on the day its follow-up is planned (Day and Week views), or in that day’s cell (Month view). An overdue follow-up stays visible today, in pink, with how late it is (D+3).
To change its date, drag it onto another day. On a phone, tap it and pick Today, Tomorrow, In a week or another day. Clicking it also lets you open the record.
The new date replaces the one on the record (and its “every…” rhythm, if it had one). The follow-up agent leaves it alone: it is your choice. Viewers see follow-ups but cannot move them. Nothing is written to your Google Calendar.