change, be transformed
渝 centers on a fundamental change or transformation, often implying a shift in state or condition.
渝 combines 氵 (water) with 俞, which likely contributes the sound. The idea of water changing or overflowing may connect to the meaning of transformation.
Water 氵 is never the same from moment to moment; it flows and changes. The right side 俞 reinforces the idea of transformation: 渝 means change.
For ユ, imagine you changing your mind: you -> ユ, and your decision transforms like flowing water.