How-to
How do I change every remaining date in a series?
In short
Edit the session's time or repeat pattern once and every date in the series follows.
Open the session page and click Edit details.
Change the Start or End time.
Change Repeat or the days of the week if you need to.
Click Save changes.
Good to know
The new dates are made again from your settings, so a name you gave to one date is not kept.
This is blocked once any date has check-ins. Nothing is saved in that case.
Dates you removed stay removed.
Times use the session's timezone, which you can change in the same form.