So after I render certain videos they turn blurry and I am unable to clearly see the footage. Is there any way to fix this? and how would I go about this?
Can you post a screenshot of your render settings? (File > Export > Media)
Your sequence resolution is too low: 640 x 360, and your output is 1920 x 1080, so it will be blurry anyway
Is there any way to change this so it won't be blurry?
No wonder it's blurry. You are trying to make a stamp (640x360) into a billboard (1920x1080).
What resolution is your source?
I'm not sure, how can I find out?
Select the clip in the project panel. Go to File>Get Properties For>Selection. Screenshot that and post it here, please.
You're starting with 4K footage and somehow it ends up in a 640x360 sequence.
Create a new HD sequence (1920x1080) and drop your 4K footage into that. If Pr shouts at you, choose the option to scale the footage to match the sequence settings.
Export that sequence with the same settings you used to export the other one and your video should be nice and sharp.