Newer writers tend to jump from head to head within a scene, and often they're not aware of what they're doing. (That style of writing isn't wrong but it takes great skill. Often called omniscient POV, I'll discuss it later.)
Let's say you've chosen first-person POV. You cannot possibly know how another character feels or thinks. Suppose you're in first person and you look at Jamie. "His angry countenance frightened me." How do you know he's angry? You can assume such an attitude, but maybe it's only indigestion or he's thinking of his loss in a bad business deal.
Try it this way: "The look on his face frightened me. Jamie had a right to be angry . . ."
Choose one POV and stay with it.