Plants look different! sum drooping! help with how to fix it

I have about 6 plants and the tops of the plants look good except the bottoms of them are slightly drooping and turning yellowish i have sum pics of them can someone help me how to fix that

over watering or underwatering?

looks maybe overwatered

yea well i water when the soil is relatively dry but recently i noticed that they dont have enough water cuz the passed few times the tops been a little droopy!