This issue relates to a feature request which I will submit separately. In the meantime, here is what I posted about this problem in the Acrobat Pro "Editing & Exporting PDFs" forum:

As described in a related "PDF Page Size" message thread, I am needing to change the font color of all - or a specified range of - pages within a 200-page PDF file, from dark grey to black. As stated in that separate thread:

In experimenting with changing the font color in a fully-justified three-column text document, in Acrobat Pro XI (Windoze 7 Professional), I am having disappointing results. The 9-point Times New Roman text is already solid black, but when I select an entire column of text and then re-select the black color swatch, the text slightly changes size and completely re-flows itself - which not only leaves "orphan" en-dashes between syllables of hyphenated words, but also causes the document to lose its exactness of layout compared to the original.

It is difficult to me to characterize this behavior as anything but a program bug, but regardless of how one chooses to categorize it, a forum user has since confirmed to me that Acrobat Pro DC exhibits this behavior as well.

In any case, even if one is willing to accept the undesired font re-sizing, I would like to see Acrobat Pro XI have the ability to change the font color of all pages - or a specified range of pages - within a given document, in one pass. Right now this process must be laboriously applied, one page at a time.

Attached is a single-column, fully-text-justified sample PDF fileI.

In the text editor, please do a Select-All, and then choose the Black
color swatch.

This enlarges the text slightly, while at the same time re-flowing
it within the column - and thus creating orphaned en dashes and
extra spaces where there had been hyphenated end-of-column words.

Thank you!