Ryanair flight schedule amendment

Vendee

We are booked for a return trip from Stansted to Marseilles in the second half of June. To be honest, I fully expect the flight to be cancelled closer to that date because of the virus situation but we will have to wait and see, In the meantime I've received a couple of emails from Ryanair informing me of a time change on the return flight. Its only 20 minutes so its no biggie and I know that the change has to be more than 3 hours before I can ask for a full refund but the emails are asking me to click on a link asking me to accept the change. I've got two questions. Firstly, if I accept the change and they subsequently change the time again, does the 3 hour refund criteria start from the new departure time or the original departure time? Secondly, what happens if I don't click the link to accept the change? Thanks in advance.