Warmlight allows you to edit many parameters before you take a photo. If you don’t know how to access them - please check this guide.
The app’s Exposure settings combines both ISO and Shutter speed settings, that is why when you choose Exposure adjustment - it switches off adjustments for ISO and Shutter speed.
If you want more precise adjustments - you might consider editing ISO, Shutter speed and even Focus individually with a separate slider for each setting:
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