At this point you should have new eyes, hair, and ears (you should have two new ears). For the mouth, choose one of approximate size to your own, or one that can be easily scaled without looking silly. In other words, if you have a huge head don't choose a student with a tiny mouth. We will follow the same steps we followed with the other features.

1. Open your picture in Photopea
2. Open the picture of the person whose mouth you wish to use
3. Use any Lasso Tool to draw a selection area around the mouth
4. Copy and paste the mouth selection onto your face document
5. Rename the new layer containing the mouth to Mouth
6. Transform the new mouth so that it matches the scale of your head
7. Position the new mouth on top of your old one
8. Use the Eraser Tool with a soft, round edge to trim any background or remaining face parts from your new mouth so that you have a nice, soft edge that blends into your face
9. Use Photopea's Adjustment Tools to make the new mouth's skin tone match yours

It is at this point that you may run into a slight problem. If you are smiling and the new mouth is not (or the other way around), you may notice that the new mouth does not look very realistic. Take a look at the graphic below...

Because my original guy was not smiling and the new mouth is, it is obvious that the mouth is not real because the cheeks are flat instead of creased, as they would be if he were actually smiling. Compare the above image to the one below...

Notice the cheek creases and that the mouth now looks more natural. To achieve the more realistic smile, I simply grabbed the cheek creases of the girl whose smile I used and incorporated them into my original character using some smudging and color adjusting. You can do the same.

10. Determine if your cheeks need to be adjusted - if your cheeks do not match your new mouth then you need to fix them or you will lose points
11. Fix your cheeks according to one of the two methods below:
    • If you are not smiling and the new mouth is, add in the smile creases from the cheeks of the student you took the mouth from (be sure to change the skin tone so it looks natural)
    • If you were smiling and new mouth is not, use the Clone Stamp Tool to remove the smile creases from your face
12. Save as PSD in your A New Me folder as ANewMe_Name.psd