On my Venu2 my running VO2 max always comes back at 35 no matter how good or bad i run. Are there any settings i need to check or am I just bad?

I would try use Garmin coach, those training plans help to increase your vo2 max.  The biggest reason why this figure stays the same is if you do the same types of runs over and over. 

I don’t know what training you do, however, switching up your training will soon get the vo2 max score up.  I doubt it’s a watch issue and is more likely the fact that you may not be training with enough stimulus to increase it.  

It’s not about how good or bad you run, it’s how well your body is using oxygen.  The more in shape you get, the more that number will increase.  If you stick with exercising consistently, it should slowly go up

Thanks both, sorry I should add a little more context. I have just switched from a forerunner 35 where my VO2 is between 45 and 50 yet on the Venu2 it solid 35 never changes. I dont mind if it is 35 I'm an old git. I'm just looking for consistancey. Since posting I have done more searching, in the watch my max heart rate was set at 139 where i can easily get 180. Hopefully this might give me a better reeading.

Yes, correction of the max hr will have a transformational change in the vo2 max number. 

Your max HR is usually calculated at 220-your age.

Good news my VO2 max moved for the first time since i got the watch after yesterdays run....whoop. I wonder how long it will take until i get an true reading.