Hi

Had my horse 3 weeks and she's locking her mouth when I go to put the bit in - help!

Try coating the bit with sugar or some other food stuff that she/he finds appealing - might help. Are u sure she hasnt got some pain in her mouth thats causing her to do it?? Could be worth getting her teeth checked

Well i guess Cazzabee have point in there in getting her teeth checked
by the way Welcome

GC

Do check and make sure there's not something wrong with teeth or abscesses round the mouth. It may be that you're a bit more "heavyhanded" than the previous owner and you may have to change your approach or be gentler - I'm a Western rider, not English and it is a rather strange adjustment for most English horses as a result.

i agree about getting the tack checked. mine used to do this and gently sticking my thumb in the sides of her mouth and a bit of bit spray worked wonders. her tack was ok she just didn't want to go for a ride!
it can take 6 months for a horse and you to get the measure of each other and get to know what each other is like.