Based on the community feedback, the main problem appears to be focus rather than just exposure. In lower light, the camera’s focusing system may not work as reliably as it does in bright sunlight, so images can come out soft or blurry.

With a GoPro Hero4 Silver, there isn’t much manual focus control available, so there may not be a specific setting that guarantees a sharp result in cloudy conditions. The most practical advice is to try taking another shot and see if the camera locks focus better.

In short: there may be limited settings-based fixes here, because the softness is likely caused by autofocus struggling in low light rather than a single incorrect default setting.