I like to live life on the edge, and helping me to do that is my Mac's Calendar app with its predliction for silently discarding all alert settings for Google calendar entries. This stresses me out as I'm just waiting for the first time I embarassingly fail to turn up for something. Today, and frankly not for the first time, I set out on a serious Google hunt to find a resolution. I now have one that's just about tolerable.
It seems the basic problem is that when you modify a Google calendar entry via Calendar, it then immediately syncs back from Google and wipes out any alert that you just configured. But you didn't want to go to that meeting anyway, right?
I can't claim original credit for my solution, but I can endeavour to explain it very clearly and add a few extra tidbits. The trick/workaround is to configure Google Calendar itself, via its web UI, to have a default alert for all newly created events. Then it seems that you can modify the alert successfully from within Calendar, to a different number of minutes ahead. However you can't remove it, so you have to just live with alerts for everything. To me that's far preferable to none at all.
You can change the setting for Google Calendar as follows.
- Sign in to your Google calendar at https://www.google.com/calendar.
- Open the settings page by selecting "Settings" from the gear dropdown in the top right.
- Select the "Calendars" tab at the top.
- In the list of calendars (which probably only contains your one calendar) select "Reminders and notifications"
- In the "Event reminders" section at the top, select "Add a reminder"
- Select "Popup" and however many minutes you want, for the default reminder.
- Don't forget to click the Save button at the top left.