For best results and picture quality...You must retrieve the images/video from the SD card in the drone by either removing the SD card and installing it into a computer, etc or attaching a USB cable to the Spark, power it on, and plug it into a computer as a separate "drive" and retrieve the pix from the Spark.
The images/videos stored on the phone are not high quality and that is what you are looking at. Don't use those as examples of the pictures/videos you have taken.
Also, reset all the camera options in the Spark to their defaults in case you inadvertently changed something?
The HQ originals can be downloaded from the Spark to the "DJI gallery" in the app and then retrieved from the app...but that is flakey and slow.