Please help me with why my plants are changing colour ??

Overwatering, these seedlings should never have been placed in 12/12 light yet. ( not even sure they are photo period) I would scrap these. And start new, start with good pots, air pots, fabric pots, aqua pots, get some good soil if you want to grow in soil. (Personally I recommend coco mixed with 30% perlite just my preference) a decent light whether LED or HID, and a grow tent or you can build one in a closet/small room with some Mylar on the walls for reflection . And choose a good nutrient line and follow a feeding schedule. But definitely read up on growing cannabis in its entirety before starting again. Hope this helps, good luck

buy autoflower seeds . they are easier to grow and they dont care about light cycle . u can give them 6 hours or 18 hours they dont care .

this is the smallest flowering plant i have ever seen wow

If i look at the plants i can see, that alot ahve been going wrong here. without wanting to be mean... i say get some facts before you start again https://www.growweedeasy.com/ as this girls are photoperiods there is only on way to save the Girls, get alight, put them under at least 16 hours light, get mj_ growing soil and take them into let them reveg and start new with the revegged plant This one is already in flower..... But i dont know if want to to this or just starting new , after learned some facts about growing mj

Defintely as a result of being waterlogged. Unfortunately my friend you will need to start again. With watering when the plant is small don't fill the whole pot with water just some around the base will do and then wait until dry before watering again. As the plant gets bigger it will need water so gradually increase as the size gets bigger. It can be a bit of a learning curve when you start out but you'll get there! ✌️

this is the result of overwatering. The strange yellow and red growth in this picture has been caused by giving the plant too much water, too often. Overwatering can often cause what appears to be nutrient deficiencies. Hopefully, I answered your question and remember Happy Growing and Free your mind one puff at a time.

They're in flower... seems like you started them on a 12/12 schedule and so they started flowering immediately, which stopped any potential growth. If you are on an 18/6, 20/4, or 24/0 schedule then you don't have the right kind of light.

Start over. Read a book.

Are these 12/12 from seed? How long? Light schedule? Type of light? You have zero info and no grow diary They look nitrogen deficient, but that's bizarre unless your soil/medium literally has nothing in it. Or you burnt it with fertilizer, which you shouldn't even be using this early in the grow. Is that straight up woodchip soil? Plants do fine with just water, especially early on. Anyway, it's basically already dead, it's a miracle you have trichomes