Regarding my recent edit to my question about different versions of \mathcal{F}, I've noticed that after I recently automatically updated my MiKTeX, it's taking fonts from a different place whenever possible. Where I used to get a bunch of messages at the end of my .log file that looked like
<C:/Program Files (x86)/MiKTeX 2.9/fonts/type1/public/amsfonts/cm/cmbx10.pfb>
the messages now look like
<C:/WINDOWS/Fonts/cmbx10.pfb>
Is there anything to do about this? The only character I've so far noticed looking different is \mathcal{F} (I'm getting the "old" one instead of the "new" one; other \mathcal characters look the same, and I'm still getting the current \delta and the math arrows with the bigger arrowheads).
Currently I'm using pdfLaTeX, pdfTeX Version 3.14159265-2.6-1.40.18 (MiKTeX 2.9.6400), and TeXworks Version 0.6.2.
EDIT (1/29/2018): I recently automatically updated my MiKTeX again---currently I'm using pdfLaTeX, pdfTeX Version 3.14159265-2.6-1.40.18 (MiKTeX 2.9.6600), and TeXworks Version 0.6.2---and it seems to be taking fonts from the old place once again (i.e., not the place on C:/WINDOWS). And thus my \mathcal{F} and all other characters look to be in the current form. I don't know what I did.