Error in drawing 2D ultrasound ROi with slicer

When I finished sketching the ROI of an ultrasound image and then opened another patient’s image to prepare for sketching, I found that the ROI that had just been sketched appeared on another patient’s image. Where is the problem? Please help take a look, thank you.

You need to be sure to close the scene (from the file menu). Otherwise the existing segmentations are retained.