Scanning

I'd check setting in two places:

Check your Acrobat Preferences, and see what your default is set to for magnification:

I would also open up one of those scanned PDFs and check the Document Properties/Initial View tab.  Is that 175% baked into one of those settings?

I don't have access to a Fujitsu scanner, but if the opportunity to view your scanner software options is available to you before hitting the scan button, I'd poke around to see if your issue is set there.

Good luck,

Dave

Unknown because we do not know how you set up the scan. 

First off, Acrobat cannot scan. Rather, it uses a linkage software known as Twain that allows your scanner's software to link to Acrobat. So, when you're scanning from Acrobat, you're using your scanner's software. So, any issue with the nature of the scan is an issue with your scanner's software, it's not Acrobat.

I've been scanning since 1991, but have never worked with a Fujitsu scanner. I do not know its interface at all. Perhaps, its settings are sticky. At some point, the resolution of the scan was set to provide 175% enlargement. The next time you start a scan, please look at the settings and see if you see anything about enlarging the image. If you can find the manual to your scanner's software, I'd suggest you look in there.

Good luck!