The Capitalization Conflict
macOS, sharing much of its core text-handling engine with iOS, attempts to help users type faster by automatically capitalizing the first word of every new sentence. While this is fantastic when typing a quick iMessage or a casual email, it is incredibly frustrating for programmers, command-line users, or anyone writing technical documentation. If you are typing a bash script, a list of lowercase variables, or a specific URL, macOS might stubbornly jump in and capitalize the first letter after a period or a hard return, forcing you to constantly hit backspace to correct its “correction.”
Restoring Case Sensitivity
To retain complete control over your keystrokes and stop macOS from automatically capitalizing words at the start of a sentence, you must disable the auto-capitalization feature globally in your keyboard preferences.
Click the Apple logo in the extreme top-left corner of your screen and select System Settings from the dropdown menu. In the left-hand navigation sidebar, scroll down near the bottom and click on Keyboard. On the right-hand side, look for the “Text Input” section and click the Edit… button next to “Input Sources.” A small floating window will appear. Look down the list of toggle switches for the one explicitly labelled Capitalize words automatically. Click this toggle switch so it turns grey (Off). Click Done to save your changes. From now on, macOS will respect your exact keystrokes; if you type a lowercase letter at the beginning of a line, it will remain permanently lowercase.