Q.leaves are turning yellow
Leaves are turning yellow but only water twice a week.
I can't give a very good answer, because I don't know what kind of plant you have, or where you're located. In a general way, however, I can say that the first thing you should do is investigate the actual soil moisture. You can do this in several ways: https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/testing-moisture-in-plants.htm
If the soil feels really wet just before you water, you're watering too much; if it feels completely dry, you're not watering enough. If you don't think the problem is soil moisture, look carefully at the leaves to see if they have any kinds of marks or insects on them. This article might give you some pointers: https://www.gardeningknowhow.com/plant-problems/environmental/plant-leaves-turn-yellow.htm