Remove knob, with flashlight look down top of shaft see a slotted screw that screw is flame adjustment.
To adjust, light burner, turn flame to low, with screwdriver turn screw rite till flame is at desired hight (aprox 2mm). now turn up to high check that high is satisfactory if high is to low then adjust screw. check low again. adjust till both setings are acceptible. do for all burners
As for holding the knobs that is common with this stove, you could check to see if flame is hitting sensor the burner hole that lines up the sensor may be dirty.
Answers & Comments
Remove knob, with flashlight look down top of shaft see a slotted screw that screw is flame adjustment.
To adjust, light burner, turn flame to low, with screwdriver turn screw rite till flame is at desired hight (aprox 2mm). now turn up to high check that high is satisfactory if high is to low then adjust screw. check low again. adjust till both setings are acceptible.
do for all burners
As for holding the knobs that is common with this stove, you could check to see if flame is hitting sensor the burner hole that lines up the sensor may be dirty.