Weird photomerge behaviour

[BSC-i]

I captured a world map with specific information on it from PC screen (7 "lines" by 4 "columns", 28 "pictures" total). While trying to merge all the "pictures" together at once, it took ages and the result was a disaster. Next I tried to merge only the first "line", pictures 1-1, 1-2, 1-3 and 1-4 (attached), expecting to have them merged in that same sequence, from left to right, the same way they were captured from screen.
No matter what settings I use the sequence in resulting panorama is always 1-4, 1-1, 1-2 and 1-3, i.e. the last "picture" that should be on the left, was always on the right before the first one.
Is there a way to force photomerge to start merging from one specific "picture" (in this case, from picture 1-1)?

[D Fosse]

First of all, there is virtually no useful overlap here. Most of it is just flat blue and the algorithm can't work with that. You need much more solid overlap (Adobe recommends about 40%).

Once you have that, you can define an "anchor" image simply by putting it at the bottom of the stack. The others will align to that.

Don't use Photomerge. That's a "convenience" command that rolls three separate functions into one. You have much more control by 1. stacking, 2. Auto-Align, and 3 Auto-Blend.

BTW - for images like this, why don't you just align them manually? Should be quick and very simple.

[BSC-i]

I will try stacking and auto-align.
If this doesn't work I will align them manually, as I used to do.

Thanks for the hint.