How to see n change DPI of pdf in Acrobat Pro DC

[LLCreate]

Hello All! I'm building a puzzle book and have pdf pages for my book nearly ready to go. Prior to uploading to Amazon KDP, I need to make sure dpi is 300. I got the free trial for Adobe Acrobat Pro DC after slogging through various free tools out there. Now, I can't find how to actually ---#1--- see the DPI of the pdf I open in Pro and--- #2--- change dpi to 300. I've found some outdated how tos but it looks like the tools have moved a bit so I'm back to square one. Thanks! 

[Test Screen Name]

You can use preflight in Acrobat Pro to reduce to 300 dpi/ppi. Do NOT increase ppi by any tricks, you need to work with original graphics of 300 ppi or more. 

[LLCreate]

Thanks for your response. I have worked with vectors in Illustrator when adding graphics to book's pages but the one thing I can't get around as far as quality control is having to insert pngs of a crossword which I build via a particular software. Once I'm done with designing the pages, I've been making sure document setup is at 300 dpi and then I go to effects and rasterize at 300 dpi. From there, I export as pdf. I basically want a way to double check that dpi is 300. I have looked at "Preflight" as others recommended but I can't find where that is in Preflight. Thank you again. 

[try67]

PDF files don't have a DPI setting. Each image in the file can have a different resolution, and the rest is vector-based.

It is possible, though, to use the Preflight tool to check whether all the images in the file are above a certain PPI threshold.

[LLCreate]

Thanks. I hear you. I have looked myself but must be missing something. Could you tell me where/how, exactly, with the Preflight tool, I can check "whether all the images in the file are above a certain PPI threshold"? That would be a huge help! 

[try67]

Open the Checks list and search for "ppi". You'll see multiple such checks under the Image section:

You can duplicate one of them and use that as a basis for your custom needs. Then create a new Preflight Profile that runs all of the checks you created on a file and produces a report about all the objects that didn't qualify.

[Test Screen Name]

Oh, and the question - how do I see the ppi (dpi) of the PDF. A PDF doesn't have a single ppi. It may have several, or none. Text has no ppi. Vector graphics have no ppi. Each image/photograph/drawn bitmap/clip art has its own separate ppi.

[LLCreate]

Text has no ppi is new info to me. I understand about each image having its own ppi and vectors none. I rasterize my vectors to a setting of 300 dpi just prior to export (from Illustrator). 

[try67]

If the text has been rasterized then it's no longer text. It's an image of text. It also can't be searched, copied, etc. In that case it will have a ppi setting, of course.