Here’s a step-by-step guide on how to do this with the Unity Preset Manager:
- Setup a sprite with the settings you want, then click the Presets button
- Press “Save current to…” and save your preset. I named mine “TextureImporterPNG.preset”
- Go to “Edit->Project Settings…” and select “Preset Manager” on the list on the left
- Click “Add Default Preset”
- Search for “texture”
- Select “TextureImporter”
- In the filter box, type
glob:"*.png" - In the Preset box: click and drag your saved texture preset from step 2 into the Preset box
You’re done!
Note: You may have to delete the .meta files of already imported PNGs if you want to have them reimported with these default settings.