Selecting the text and pressing CTRL-SHFT-A again fixes it by turning All Caps off. I probably meant to hit CTRL-A (Select All), and if I accidentally hit CTRL-A before CTRL-SHFT-A, my entire document is suddenly UPPERCASE.
Apparently when this happens, I’ve accidentally hit CTRL-SHFT-A (or maybe CTRL-ALT-A depending on the version of Word?). This finally annoyed me enough that I did some research and found. Microsoft should disable the relevant keyboard shortcuts used by an impossible fraction of its userbase. This blog post has more than 120,000 views. In settings, search for toggle keys and configure Windows to play a sound when you press Caps lock. Update 2.Apr.2021: Relevant Microsoft Office Word 365 keyboard shortcuts: Closing Word and opening the document again does not fix the problem.
Other Windows applications and the light on the keyboard show that Caps Lock is actually off.
Every once in a while, I find that Microsoft Word seems to think that Caps Lock is on, and everything I type appears in UPPERCASE.
