Character expressions from slide to slide.

A variable maintains its value until a trigger adjusts it. That's why variables are so useful for tracking within a course. 

Based on the limited description provided, it sounds like the default character state shows the confused expression. It also sounds like the "emotion" variable isn't being adjusted (or, at least, it's never changed to "angry"). 

When troubleshooting an issue that involves variables, it helps to put a text box on the slide(s) that shows the current value of the variable. That lets you see whether the value is being adjusted as expected. To show a variable's value in a text box, go to INSERT > Reference, and then choose the appropriate variable. 

Beyond that, troubleshooting is just guessing without seeing the .story file. If you upload it, someone might be able to solve the issue. Here are the best practices for uploading a .story file:

• Only include slides that are related to the problem.
• Be sure objects, layers, motion paths, and variables have meaningful names.
• If there is proprietary content, replace or delete it. For example, replace proprietary text with “ipsum lorem” text.

It’s worth the effort to learn about variables and trigger conditions, because they provide the real power in Storyline. Here’s more information:

• This post provides an overview of variables. It also links to numerous resources. The Value of Variables | Articulate - Community  
• The User Guide section about triggers includes info about conditions.  Storyline 360: Working with Triggers | Articulate - Community