Not knowing anything about your saw w/out some research, from the looks of your picture of the blade holder, it uses plain end blades. And takes a hex wrench to install the blade. Just by looking.
First off, your blade isn't centered in the blade holder. That is a must. If the blade isn't centered in the blade holders, they'll never stay in it. Your holding power is in the center of the blade holder. Next, take the hex screw out of the blade holder & have a look see at the end of it. If it's smooth, as I suspect it is, rub the end of the hex screw on a piece of 100 grit sandpaper to rough it up. This will help hold the blade. Do this to both ends.
Next thing is blade tension. Adjust your tension until you get high pitched "ping" from your blade. Then take a business card & check your blade to see if it's square with the table. If its square, & your blade holders are in good shape, you should be good to go.
In the meantime, I'll do some research to see if I can be of more assistance to you, Sir.