Have patience, these strings take an extremely several weeks to stretch and become stable, although once they’re there, they don’t move around much.
The black plastic strings look great on my ukulele, however the lowest string sounds a bit flat and stiff, and the highest string takes even longer than the others to stabilise. They sound fine and feel good under both hands. The strings are long enough that you can get two sets out of a single packet, which is fine for having spares but I’m planning on trying out some different strings as there’s definitely room for improvement.
