On an energized recepticle,
test the smaller length hole (hot)
To ground (round hole) and see if theres 120v.
If you read across the energized recepticle hot to common (larger length hole) it should read the same.
If youre still getting a bunk reading you might want to replace the meter.
1 typically means out of range. Can try changing batteries, setup looks correct. Also try flipping the leads, never heard of multimeter that can’t read neg V but maybe possible