For some reason, I can make my sprite move up, down, or left when a certain key is pressed. However, when I press the key for right, it does nothing. I've checked the code and it's the exact same as the others, with the only difference being the key pressed and the "speed * -1" part. What's going on?
Could you share your code?
I agree with bh, please share your code.
In the meantime, have you tried running the move code manually or trying a different key?
How do I do that?
I've tried taking the block out and clicking on it, and that works. But for some reason, it doesn't work with the "when green flag pressed" thing. I tried switching to different keys and that works to, but I want it to be "when d pressed" or "when right arrow pressed".
Sorry but idk how to share the code in here
Click on file 
> Open > Select your project > Share and then you can copy the url and share it with us.
You can also right click the movement script and click "script pic" to get a picture of the script, which you can also share here (though I'm not sure if the forum will let you attach images yet).
The top script does the opposite of the bottom one, thereby cancelling the movement out. Try simply removing the first script. This should fix your problem.
It works! TYSM!