Same problem and this is what i did to fix it....

In memorized transactions list select the item that you want to stop giving you the reminders on your pop up. Edit the reminder and choose "Do not remind me".  Then setup a new memorized transaction like you want it to be set up. you will be asked if you want to replace the existing one or add a new one. I just added a new one. The old one just remains in your list but as inactive because it till be listed as "Never" in the frequency column.