Jigsaw keeps jumping during cuts. are there any adjustments?

Most likely the culprit is the roller (Bell Crank #623190-00)
Unfortunately, the part is obsolete and no longer available - you may get lucky and find one on Ebay or by doing a Google search

Use a straight edge guide. Clamp it on the work so the jigsaw can run against it. Be patient and go very slowly.

There are diffrent blades for difrent makes ,Did you by the correct make e.g if its bosh by bosh blads .The slot might also be worn out if you used the wrong blade in it or the screw that holds it in is warn ,Hope this helps

get a nail file and sharpen the blade till you can see your face in it

Most of the time the cause for this is applying to much pressure on the blade as you are cutting. Remember, the blade does the cutting and you are guiding the jigsaw around the cut. This can strip the blade and wear the top of the mount. Adjust the way you cut and you should not have any problems.

You will need to obtain a new [Roller Lever Assy] from a Bosch parts dealer. Its a fairly simple install. This is a wearable part due to the pressure put on that portion of the tool during normal use.

on the front of the saw where the blade is there is going to be a little lever you pull while at the same time push the blade in the blade holder

You are not actually tightening the blade in place. The only orientation is front and back, but I suspect that you knew that...

Sounds like you are not actually tightining the blade.Pull up HARD on the quick release knob or it will not actually engauge, but it will sound like it is...and turn clockwise until it jambs, when tightening. then continue turning clockwise until know aligns with the body, and press down to park.

This is a really great tool.

There are good blades and there are cheap blades. Good blades are straighter but less tolerant of poor technique and so tend to break, cheap blades can and do bend far more. You can keep the blade straighter by not forcing the blade through the work and allowing it to cut at it's own rate and by experimenting with the speed settings on the jigsaw. It also helps if you pick the correct blade for the job: 10tpi is a bit too coarse for ripping a timber batten along the grain but fine for rough cutting chipboard. Also, it's difficult to keep the foot of the jigsaw absolutely level on 2x2 which adds to your problems.

a jigsaw is for cutting wavy lines if u want a straight cut use a rip saw with fine blade but you still can use a jigsaw must have sharp blade there is a blade u can get now from screwfix with a triangle spine on the back off the blade to prevent it twisting works fine (also do not push hard on the powertool let the blade do the cutting less likely to wander hope this is of help