When using the animation export dialogue, setting a PNG setting while "rendering" an mp4 video results in the PNG export settings reverting to default. Reproducible: always Steps to reproduce: 1. File -> Render Animation... 2. Under "File Format" select PNG Image and check the "render" checkbox 3. Click on the [...] to the right of the PNG Image to set render settings (change from the defaults) 4. Click OK 5. Re-open the PNG image settings and note that they have reverted to default. Workaround: If you export the project as a single image using File -> Export -> PNG image and set the PNG quality settings in that dialogue, then the renderer will use those settings instead.
This is fixed in 4.0