An abbreviation can be correct for your project even when Word automatically expands it into something else. First confirm that characters are being replaced as you type, rather than merely receiving a spelling underline or a suggested correction.

Reproduce the behaviour in a disposable document using the exact abbreviation and the punctuation or space that follows it. Record both the text you intended and the replacement you received. This gives you a specific rule to inspect instead of turning off several unrelated writing aids.

Find the exact replacement pair

In desktop Word for Windows, open File, Options, Proofing, AutoCorrect Options. On the AutoCorrect tab, type the unwanted trigger in Replace, select the matching list entry and choose Delete. Leave Replace Text As You Type enabled if the other listed replacements should continue working.

Microsoft states that this list applies across Office applications that support AutoCorrect, so adding or removing an entry in one application affects the others. Word for the web does not provide the same entry-addition and removal controls. Make the change in the desktop environment where you have identified the rule.

Before deleting a shared-use entry, keep its Replace and With values in your working notes. If the abbreviation is only suitable for one unusual document, decide whether a broader list change is appropriate for your everyday work.

Test both the exception and a useful correction

In the disposable document, type the intended abbreviation again with the same following character. Confirm that it remains as entered. Then test an unrelated correction that you rely on. This distinguishes a removed rule from accidentally disabling the entire replacement feature.

If the unwanted change persists, return to the exact symptom. Automatic capitalisation, an AutoFormat action or another typing tool may need a separate investigation. Do not keep deleting unrelated entries because their wording looks similar.

Review existing passages where the earlier replacement may already have occurred. Removing a future typing rule is not evidence that old text has been corrected. Check each affected use in context, particularly where the expanded word is plausible but changes the meaning.

Keep the change limited to the confirmed cause and note the reason for the exception. That makes a later return to the original rule a deliberate choice rather than another unexplained typing change.

Sources: Microsoft: AutoCorrect entries; Microsoft: AutoCorrect access.