If you have modeled the apple using reference images showing each side, you can simply stencil the texture on it in the corresponding viewpoints (front, left, top, etc).
Start with an aligned view like View > Viewpoint > Front (Numpad 1) and paint on it. Paint mainly in the center of the apple because there will be massive stretching at the edges of the object.
Then switch to the next point of view (e.g. View > Viewpoint > Right (Numpad 3)) and use the corresponding image (part) for the stencil. Repeat the steps for all visible sides of the apple.
At the edges, a seamless transition results if you focus on the center for each side.

Clone apples. This is the same apple, three times.
Addendum
Looks like you followed this tutorial. The used images seem to have a perspective, lens distortion, or are photoshopped, or are not turned by exactly 90°. I'm not sure. But something doesn't look right.

Used images for the stencil / screenshot from the video
Compare the second image in the first row (image 2-1, "left"), and the image 1-2, ("front"), and 2-2 ("right"). On all three images, you can see the bright yellow area. But in the images of the two side views, the spot should only be visible as a very small strip, shouldn't it?
In consequence, you need to adjust it a bit. Begin with the "front" view and adjust the sides a bit. Scale them up and/or move them a bit in the front direction so that the yellow area overlaps appropriately. Do the same for the "back" image (1-1) in direction of the back. If you let the pattern match, it will look good.
As you see, you can barely see the yellow area from the side:

180° turnaround - right - front - left view