Want to find an eBook and PDF Reader to read PDF easily? Here is a list of PDF eBook Readers which support both ePub and PDF formats. It gives the option of night mode, which lets you view the page as black with white text for easier reading.
Anything is possible with the right tool. In this case you need Acrobat Pro, since Acrobat is the only app authorized to edit PDFs. Even then some PDFs ask for a password when you try to make any changes. You can get a pro copy from some 'shady' sites, which I think is justifiable, no one in right mind can expect one to buy a $400 app just to change a background colour. Install, do it, uninstall. If pro version has a demo, then you can try that first. You will find 'Add Background Color' in Tools menu or right hand Tools column.
I am using Preview Version 7.0 (826.4) and I can set the Font color: Go to --> Cutout photo software for mac. 'Tools' + 'Annotate' + Click on 'Text'. When the Text Box is open for entering text, click on the color icon (next to the Font selector): Hint on where to find it: below the File Name, you should see a set of about 8 edit icons and next to those you should see the color selector icon and next to that you should see the font type selector, to the right of that you should see the font size, an to the right of the font size you should see (left, Center, and Right) selector.