Be aware of a couple of issues when you're using acronyms:
- Acronyms are typically all caps. When you add an "s" to make them plural, make the "s" lower case. This also applies to acronyms in all-capped titles: make the "s" lower case.
- Don't add an apostrophe before the "s" when making acronyms plural. An apostrophe is used for possessives, not plurals.