Standardizing text appearance. (One document I downloaded has a much darker appearance than all the others, and it's not bold.)

I have one folder where the print is dark, almost bold. All the other files are regular print. I’ve tried everything I can think of to correct the problem. Any suggestions?

Check to see if it’s a different font.

Fonts can play tricks, it could be a heavier weight of the same font.

I had to go into font book and disable certain versions of the font I was using.

Perhaps it got the outline attribute. Only accessible via the menu as it is rarely used. Format/Font/Outline.

How about converting the text in that document to the default paragraph styling? Assuming there is no fancy formatting to be preserved, that might be all that is needed.

You say you “downloaded” the text or doc. Perhaps, for example, you copied text from the web and pasted it into a Scriv document. But if what you want is sensible, uniform text, you need to use Paste & Match Style command, not simple Paste. You should probably also Zap Gremlins on the result.