Mac Calendar events not syncing accurately across devices

iCall on my Mac isn't syncing alerts across the iphone, ipad and Mac devices. I noticed on the Mac calendar's setting under Alerts says "On My Mac" no matter how many times I change it to iCloud. Example: iphone has default alert 2 hours before, on Mac for some reason it started saying the default was 10pm the previous night. I only us Apple products and would like to be able to have each calendar alert to be the same.

[Re-Titled by Moderator]