The height of the bubbles doesn't always solve everything. It also has to do with bubble placement and size. Stryc's, for example, has his characters in the same position, the main on the right and the secondary on the left. But it works because his bubbles are larger and stretch over to the right side of the panel. And since they are at the top and are at the right (mostly), they are read first, as they should be. Yours, however, stay right above the characters' heads and are rather small compared to the panel. Even though the left panel is lower than the one on the right, it's still going to be read first because it is lacking the size and L-R placement necessary to be seen as "read me first." Stryc also zoomed in on his primary character to establish that he's important while every one of your panels is exactly the same. And Jens has it right. If the reader has problems reading the "correct" bubbles first, it's not a problem with the reader, it's a problem with the layout.
Sorry if that was really long, but I learned that from a comic artist.
