Inaccurate and misleading watch readings

I bought the Polaroid GPS Sports Watch from Clicks about 2 weeks ago. I’ve set up everything that needs to be set up. I use the watch for my steps, playing squash, heart rate while working out and resting heart rate.

For the past couple of times I’ve played squash it rated my heart rate at a maximum of about 121 bpm. When I cycle at the gym my heart beat reaches about 101 bpm. I use the heart rate on the bicycle which indicates 121-130bpm.

This Polaroid watch is seriously inaccurate by at least 20-30 bpm less on average. My heart rate when playing squash sessions from past experience, my heart rate is between 140-170bpm.

My resting heart rate was showing as 49/50bpm which is seriously inaccurate.

Is there a way to reset the watch to see if I can get more accurate readings from the watch?