If your nail feels tight or too small
Gently widen the curve by using a warm cup of water. Press the curved side of the press-on nail against the curve of the cup for a few seconds. The heat helps relax and open the nail so it fits more comfortably.
This works especially well for flatter nail beds.
If your nail is a bit too large
Use a nail file to carefully shave down the sides of the nail. File in small amounts (about 2–3 strokes per side), then check the fit before continuing. Once you’re happy with the size, apply a thin layer of clear nail polish or gel along the edges to seal them and help prevent lifting.