ue4 distance field shadows poor quality

How improve far distance shadow? Now look like very low resolution

First picture Light Source Movable, Second picture Light Source Stacionary but preview after bulding the same like movable, what is going on? The Distance Field Shadow is on. Second picture far away distance shadow is nice smooth

Ok I do as you tell so check pictures the same s* quality shadow after build light, but when I change light to movable and back to stacionary (only just for make light preview! every setting the same) is perfect quality