polyfluoroalkyl substances (pfass) is a large family of surfactants with different uses and environmental and health properties.

How would the previous sentence be correctly capitalized?
Answer: Polyfluoroalkyl substances (PFASs) is a large family of surfactants with different uses and environmental and health properties.
did someone email you a a8 file and you're not sure how to open it? maybe you have found a a8 file on your computer and wondering what it's for? windows might tell you that you can't open it, or in the worst case, you might encounter a a8 file related error message.

How would the previous sentence be correctly capitalized?
Answer: Did someone email you a A8 file and you're not sure how to open it? Maybe you have found a A8 file on your computer and wondering what it's for? Windows might tell you that you can't open it, or in the worst case, you might encounter a A8 file related error message.
and in order to thank all the uses' support and also as a return, dll suite introduced this free download service to help millions of pc users suffering from dll errors like itvres.dll.

How would the previous sentence be correctly capitalized?
Answer: And in order to thank all the uses' support and also as a return, DLL Suite introduced this Free Download Service to help millions of PC users suffering from DLL errors like ItvRes.dll.
all are simply but stylishly furnished, and come with wi-fi and air conditioning.

How would the previous sentence be correctly capitalized?
Answer: All are simply but stylishly furnished, and come with Wi-Fi and air conditioning.