Hi Grace,
The Mirror Modifier is using the Object's Origin to Mirror around:
You can use the Console as Mirror Object, maybe that helps (depends on where the Console's Origin is, of course.).
You can also;
Switch to Object Mode, SHIFT+S > Cursor to World Origin. And then Add an Empty and use that as the Mirror Object in the speaker's Mirror Modifier.
(And there are many other ways to fix this.)
Yeah your origin is where the 3d cursor is...
Go to object mode > Press SHIFT+S and select Cursor to World Origin > With the speaker object, Press RMB and select Set Origin > Origin to 3D CursorThe mirrored speaker should jump to the correct position.
Also consider starting with the Blender Basics Course:
https://cgcookie.com/courses/blender-basics-an-introduction-to-blender-4-x
It teaches you all these little goodies, since Press Start is actually not very super beginner friendly.