My new hear race monitor

I bougth today my first heart rate monitor. It is a Aptonia CW700 (Aptonia is a mark of Decathon). Now I'm exploring the features of my new toy! The only difference from the kids to the adult people is that the adults bought more expensive toys!! I bought this for two main reasons: the heart rate monitor to start monitoring my runs and also for the chonometer features, because the watch I usaly use only give me the time spent from the begining and I also need the lap memory function and the intermediate counter to use during my races (or tranning) to check my km pace.
Now I'm trying to find out how can I disable the sound emitted every heart beat.

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