how to get correct yardages from the tee

Is the watch set to give you metres or yards in the settings?

you are right, i forgot to change it, but even so, i think the yardages are still way off

You have the PlaysLike feature turned on so will not get a true distance to the green.  The PlaysLike distance feature accounts for elevation changes on the course by showing the adjusted distance to the green. The little down arrows by the distances show that the hole plays shorter than the stated yardages. Does the hole slope down significantly?

To turn off Plays-Like, just tap the numbers.  The little down triangle to the left of the numbers indicates the green is below you.  A square would indicate it's about the same level as you.  And up pointing triangle would indicate it's above you.

Another thing that can impact the distance is if you are on a dog-leg hole.  The watch will give the distance using the mid points of the dog-leg turn rather than direct distance.  If you use a range finder, that would give you direct distance (cutting corners).

Thanks, I will try

100 yds difference? Is the green straight down?   How was it once you got off the teebox? Did your drive distance and your distance into the green add up?

not really, the course has 250, 200, 150 and 100 yards maker, when comparing to the reading from watch, the 200 yards maker had a btter agreement with the watch reading