To add watermark, go to Camera App > Go to Camera Menu > Go to Watermark and click your picture.
If you want to add watermark on the already captured pictures, Go to Gallery > Select the picture where you want to add watermark > Click on Edit > Select Watermark option.
Honor Holly 3 comes with 16GB Internal Memory (ROM) which can be expanded up to 128GB via MicroSD card.
No. Honor Holly 3 does not have earphone or headset as part of standard in-the-box accessories.