will be helpful to see a vid of you failing the jumps to understand the problem.
I'm gonna give you an answer based on my experience:

jump a6 requires 2 main things - getting a high jump & doing basic air strafing.

The easiest way is shooting at the floor + crouch-jumping
you walk forward -> look down -> shoot (only m1) -> crouch + jump

if you shoot too late - you won't get enough height
if you shoot too soon - you won't get height at all
you need to shoot a millisecond before crouch-jumping
but often it is easier to press everything at the same time.

the first obstacle could be the ceiling:
if you jump too early - you bump into the ceiling
if you jump too late - your flare misses the ground
make sure you jump near the edge and be in the sweet spot.

the second and most common obstacle could be the boxes in the front
if you don't strafe to the left - you'll bump into them
if you don't let go of 'w' when you jump - you won't be able to strafe
the moment you jump - let go of 'w' and start using 'a' or 'd' in sync with your mouse turn.
also - holding crouch while in the air is important because it makes you smaller so you could fit inside the free area.

some common mistake is jumping into the wall with full speed, this specific jump doesn't require you to turn right and explode the flare, just shoot the floor and do a simple crouch-jump, then start strafing your way through the jump.
you strafe right (to avoid wall) -> you strafe left (to keep going) -> you strafe right to hit the window floor, without bumping to its upper tip.

jump b1 - get enough height as explained above. avoid bumping into the ceiling.

Not all heroes wear capes.

The advice for a7 helped me get past a 30 minute stumbling block. Thanks a ton.