My 965 incorrectly measures distance.

8179024 said:

Also the data screens keep changing on their own and adding in multiple strava relative efforts?

Do you mean the screens move or the date fields with the screen change?

Do you have touch Screen enabled on that activity? If you press on a field it will allow chnages , maybe it is getting pressed ?

Re I have completed two walks today totalling nearly 2 miles and both walks have been logged at over 5000 miles each?!

Did it get GPS lock at the outset correctly? What GPS setting is being used?

Is this a new watch or has the behaviour suddenly change?

I use mine daily with no issues when recording walks.