When resetting the cumulative and daily totals the manufacturers instructions are a little unclear.

The RAIN button is a rocker and if contact is made on both Since/Rest and Search simultaneously the reset is cancelled.

You should first use the Since/Reset half of the button to see the last reset date. Then hold down the Since/Reset button on the left hand side for a few seconds until total resets. Do not apply too much pressure as this will hold down both halves of the RAIN rocker button

If the Since date reverts back to time before resetting then start the procedure again.