hi, since 6 months my elevation gain is incorrect each time I run. What can I do to sort this out?
You can try the following:
Reboot/reset the watch.
Clean the barometer port.
...and do a search of this forum to find lots of information
How to clean the barometr port?
Give it a bath in lukewarm water with some mild detergent. Leave it submerged for some time, shaking it gently several times.