To use the Englishman's technique from Post #4 with a preattached DSMB, use what
@outofofficebrb showed you, just above:
https://www.scubaboard.com/community/attachments/aec72c13-fdcc-4fad-8ed5-209077b2c98f-jpeg.533978/
Just clipped thru a hole in the spool, if you play with your bolt snap, you'll quickly see that by twisting it in a not very unusual way, the little button for your thumb that actuates the bolt slides against the spool, pulls the bolt back and boom! The bolt snap has detached! See
@The Chairman's video in Post #9. A VERY common problem, just as you noted.
That's why the DSMB+spool really belongs in a pocket. But if you have to carry it loose, then use the picture above. It's done by threading a loop of line thru a hole, clipping the bolt snap to the loop, then wrapping the loose line around the shaft of the bolt snap before clipping the bolt snap back to the
line, not to a hole in the spool. The wrap keeps the thumb latch from being engaged except by your firm pressure. It's not wrapped so tightly that you can't get it apart, but prevents the inadvertent opening of the bolt when the DSMB flops around on your D-ring, or wherever it's attached.
IMPORTANT: Since you're pulling a loop from the end of the line where you've already created a loop to attach the DSMB, the "loop" you pull thru the side hole has TWO strands (both of the legs of the loop that you created before, from the Englishman's video in Post #4). Thus, when you wrap the loop around the bolt snap and finally clip the loop off with the bolt snap, you are capturing FOUR strands of line:
https://www.scubaboard.com/community/attachments/69b69051-0ad8-44aa-8dcc-7e166de18bb6-jpeg.533979/
To answer
@laikabear 's question, when you unclip the bolt snap from the line, the loop you pulled thru the hole of the spool slips back in, and the already-attached DSMB is ready to spool out. When the DSMB is at the surface, tension it up, and clip the bolt snap to the line and thru a hole of the spool.
The only hard part is learning how much of a loop to make. I use about 8" of the final loop you created, with
both legs threaded thru the nearest spool hole to create a four-strand loop with two 4" two-strand legs. That seems to be enough to wrap around the neck of the bolt snap without having all the pieces flopping around on extra line, and pulls my DSMB up tight against the spool for carrying.