How do I properly apply a hair cushion to hide gray hair?

Why do gray hairs grow so fast?

It feels like the roots are already growing out just two weeks after dyeing them.

yo. this;;

At first, I tried a device where a liquid dispenser was combined with a brush; pressing the back button dispensed the liquid onto the brush, and you would apply it to your hair like a comb to cover it. Then, I tried a lipstick-shaped one that covers gray hair, but both were inconvenient because they got on my hands.

I tried getting a hair cushion this time... but how should I apply it properly? It feels too drying if I just pat it on. Should I use hair essence or apply it when my hair is still damp?