I'm trying to insert an image into my question prompt, and I've watched this video for help.

However, the toolbox in the video does not appear when I edit the question text, as you can see in the attached image.

Is the toolbox missing because of my version of Lime Survey (I have Version 2.65.0, so I find that hard to believe, since the video is of 2.50)? How do I get the toolbox to show, and if not that, then is there a way I can still get the image inserted into the text of the question, even if I cannot get the toolbox?

You can change this in
"Configuration / Global Settings / General / Standard HTML Editor"

Seeing your attachment I assume now it is set to HTML source.
So you just enter the HTML code to insert your video.

Or you change to "embedded" and have the full editor features available.

So afterwards you may change your username.

Best regards
Joffm

Thanks for the quick response! Unfortunately, my Configurations tab only has the option "Template editor" as a clickable option. Settings is there, but I can't select it.

But I'll try the HTML code, hopefully that will work. And yes, maybe then I can change my username.

Click on your username at the top-right, then click "Your account", then select "Inline HTML editor".