Question

If dark matter makes up 90% of the universe would that also mean that it makes up about 90% of every galaxy?

Answer 1

Pretty much by definition, since there isn't anything in the universe besides galaxies. I don't think anyone imagines there are vast stretches of dark matter between galaxies, if that's what you mean. If nothing else, the idea was invented to explain why outer stars in a galaxy orbit in ways that suggest there is more matter in the galaxy than can be seen. There's no way we can observe the influence of any supposed dark matter except by how it influences visible matter -- i.e. galaxies. ("Dark energy" is another story.)

Answer 2

Dark matter does not necessarily make up 90% of every galaxy as it is not uniformly distributed amongst them. Spiral galaxies tend to have more dark matter in their haloes than elliptical galaxies, and dwarf galaxies have the highest percent composition of dark matter in relation to their size.