Cannot change Calendar event alerts for 'On My Mac' on Mac

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Cannot change Calendar event alerts for 'On My Mac' on Mac

Unable to change alert time for Events on Calendar app on Mac. When I try to change the Event alert from 1 day before to "none" (or any other option, i.e. 5 minutes), it will not keep the change. I'm able to do it for the iCloud account, but not the "On My Mac" account. I am the administrator, and I'm logged in. Notice, too, how the "Use these default alerts on only this computer" is greyed out, as well. I don't need alerts one day in advance, so it's a bit annoying to have the alerts pop up a day in advance on my iphone and computers, as well. Any help with this?

Mac mini (M1, 2020)

Posted on Mar 20, 2026 8:52 AM

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Answer 1

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6x6

Level 7

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Mar 20, 2026 12:44 PM in response to Bodhisan

If you are only using iCloud calendars (as you indicate you want them on all your devices), the "On my Mac" alert settings are irrelevant.

The ones you need to change are the iCloud alert settings. For iCloud, do check the box “Use these default alerts…” so both your Macs and iPhone use these default settings.

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Answer 2

6x6

Level 7

20,667 points

Mar 20, 2026 11:53 AM in response to Bodhisan

It is normal for this checkbox to be grayed out for the “On my Mac” calendars, as there are no other devices involved if those calendars are only on your Mac. (That checkbox is also grayed out on my end.)

It is abnormal that the alert settings for the “On my Mac” calendars do not stick. There might be a way for correcting this issue but I’m surprised that you receive a 1-day before alert on your iPhone. This would indicate that the iPhone is using an iCloud calendar.

So a few questions:

Do you actually have calendars exclusively on your Mac? If not, those alert settings are irrelevant.
In the iCloud alert settings, did you check the “Use these default alerts…” so that they propagate to your iPhone?

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Answer 3

Bodhisan Author

Level 1

32 points

Mar 20, 2026 12:34 PM in response to 6x6

I want my Apple calendar app to be accessible/make universal changes on all of my devices, so it is not exclusive to any one device - all of my devices are using the iCloud calendar for merging.
I'm not sure if I fully understand this. That iCloud alert setting says "Use these default alerts for this computer." But to answer your question, I have not checked that box - especially since it allows me to set the alert to "none." But I'll try it.

I have two Macs, a Mac Mini - which is the one that won't let me change the one-day alert, and a Mac Air, which lets me set the alert to none, but which oddly, like my iPhone, still gets the one-day in advance alert. If that helps with your diagnosis.

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Answer 4

Bodhisan Author

Level 1

32 points

Mar 20, 2026 2:10 PM in response to 6x6

I did check that box for iCloud and set an alert for tomorrow - a few minutes ahead of the time I created it, and I did not get a one-day alert on it, so I'm hoping it is fixed - thank you! For my thinking, that was counterintuitive, but I get it. :)

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