Imported image as plane does not have accurate colors I am trying to make a music video and import my logo (.png), however the logo does not have accurate colors (it has clear white background, but blender shows it as gray): link to screenshot #1

These are my material settings, I hope I have started correctly: link to screenshot #2

The circle I created behind it is also a bit grayish, so there must be something basic I'm missing. link to screenshot #3 with the circle behing the logo

Switching the mode does not solve the color problem, as mentioned in the comments the background of my logo is still gray afterwards.

Solved: I needed to add/move the light on top (to face the planes) and re-insert the image in order to reset to default settings. Result: link to imgur.com
I believe you are on the right track... 

Switch from Filmic to standard but not on the image or material like you did. 

I actually didn't realize you could do it image by image like that but I think you need to switch it on the actual world scene. 

Look under the "Scene" tab where you switch from EEVEE to Cycles... at the bottom look for "Color Management" and "View Transform" then switch that from Filmic to Standard.