Quiz Slide & Buttons

Hello! I've created a quiz and I'm trying to make sure I follow accessibility protocol. I was trying to decide if I should add I put PREVIOUS and NEXT buttons on the slide? If so, does that change the score. In the process of trying to determine that, I noticed my slide score is not adding up correctly. If I choose A (4pts) each time for 5 questions, I get a score of 16. 

The only thing I can think of is that I did some edits to the Choice A button. I finally just deleted the button and copy/pasted the Choice B button in its place. I updated the object triggers. 

Can you help me figure out why the score is not adding up correctly? 

I also need advice on if I should add PREVIOUS and NEXT buttons. If I do, will it affect users scores if they go back to a question. I really don't want to have to go back and program if they change their answer if it is too complicated. This is just a project for my portfolio. 

I can message my files if I need to . 

Thank you!

Meleah