This is all rather basic, although it is something key to remember when making the lighting more even. Surfaces range from being flat to randomly corrugated.
Just some examples of varied surfaces include but not limited to clothing, walls, faces, sporting equipment, grass, plastics and tree bark.
All of theses surfaces pose a great challenge when working to control the shadows. Please notice that I used “control” instead of “end” or “remove”. We do want some shadow for contrast, but we do not want the shadow to be uncontrolled.
The light spread in your direction is important for the fact that shadow a created at a low angle is going to be “darker”. Changing the angle should allow the light to spread more evenly across the surface. Experience is one of the best ways to learn what is occurring and how to resolve the issue.
A large illustration of this topic is the sun against any semi-solid object. The shadow is cast because the object stands in the way of the sunlight’s pathway to the ground. The direction and depth of the shadow changes as the earth travels its pathway around the sun.
This change of shadow depth and place is effectively the same as moving the light. I have said there is one good way of learning what is happening and how to resolve it, by experience.
Experimenting in available time will help. Give yourself some projects that emulate the same problem. Work out other lighting difficulties without over working yourself. I often will push too hard and run out of creativity when I should stand back asking questions. Questions should lead to answers, answers can lead to solutions and solutions make the way (specifically for us) to better photos.