little bit iffy all the way. mayby the bb was 3b to much, but on this stakes u want more often just fold to the 3b. if u really want to exploit the bb and give him some fold equity raise higher.

as played aldo the river bet is small but where still have to fold

This hand has plenty of equity to call and has weakish blockers to strong hands. The combination means that is unlikely to be a profitable 4-bet in a vacuum, so you should call preflop.

Postflop play is standard. Folding to small bets with top pair is highly exploitable and readless would be a large mistake.

Q9s is good enough to call pre.
Something like A9o or K7s would be better hands to 4-bet with.

ty so instead of a Q9s what hands would u choose to 4B i also use A6-A8 s

If you compare a players BB 3b v btn open to bb sq v btn open sb cc, you will find the sq range is significantly tighter and stronger. This makes boith your plan and hand choice pretty poor.
As the others point out, Q9s is plenty good enough to call 3b IP, so just do that.
As played, flop and turn fine, river once the bb sq's/calls, x/c flop - not knowing if SB will x/r - then makes a 50bb river bet, you'll likely see a strong hand more often than in theory you should.