How about drag/dropping a couple screen-grabs into your reply box?
First, one of the full Program Monitor window ... and especially, we'd want to see what the figure in the lower right corner is set to ... Full, half, quarter, what? That's the resolution it will use for playback. You can change that of course.
Second, how are you getting them into the app then onto a timeline?
Ingesting from the Media Browser panel is best, then creating a sequence by simply drag/dropping a clip from the Project panel onto a blank timeline panel works very well to get a proper sequence setting for the media.
And ... a bit of info on your computer is nice ... OS/CPU/RAM/GPU, the number-dot-number version of PrPro (as in 12.1.2), and the media you're working with. What created it ... camera, screen-recording, drone ... ?
I cannot upload my images they say the file type is forbbiden they are saved as PNG files, I even coverted them to PDFs. Not sure what file type is supported. But I can tell you the full program monitor is set to half, I have the files on my computer in a folder, I then insert them into the project panel and from there I drag them onto the timeline. My version of PrPro is 6.0.0 I believe, and I am working on a laptop. Intel(R) Core(TM) i3-3217U CPU @ 1.80 GH Processor, 6 GB of RAM. With Windows 10. And the files I am working with are from a playstation 4 video capture. If you can tell me supported image types I can upload all those images for you but I believe all the info you need should be in my text. Thank you for the help really loving premiere and look forward to using it a lot more.
Video capture files can be tricky, especially with CS6. You might need to use the free download app Handbrake to convert those to constant frame rate (CFR) as they are probably variable frame rate (VFR) which they probably are.