How to change lower case am/pm on the menu bar to uppercase?

Solution 1:

Since my system is german, I'm not 100% sure, but try this:

  • go to 'Language & Region' in the System Preferences

Language & Region

  • open 'Advanced Options'

Advanced Options

  • go to tab 'Time' and see if you can customize the way it's displayed

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Solution 2:

Go into System Preferences -> Language & region, click on the button labeled "Advanced…" in the lower right, select the tab labeled "Times" and and then enter AM / PM as the abbreviations for Before / After noon in the lower left text fields.