The formula for the output voltage is: 0.6v x (1 + R1/R2)
In my early attempts to use MT3608 i used a schematic quite like the one above, a pot and a single resistor.
With that setup, i dont know why but i did fry several chips.
Also, the capacitors i use are 25V versions so i have to limit output voltage to that limit too...
Now, i use a 47k resistor in the upper branch of the voltage divider a 2.4k on the lower branch and a 50k pot in the middle. interestingly, the pot is actually affecting voltage only at about 1/3 of its turns... so with the pot in its original position full left, i get Vout~Vin After several turns it starts boosting.
Now, i read somewhere that in the modules with only a pot on the upper voltage divider branch, you need to bridge the loose end of the pot to the center pin and then it works all the way....
Another well known variant is modules with 68k resistor in series with a 30k pot and a 2.2k resistor in the lower branch.
The most "weak" parts in these modules though are the caps...
Also, adding a 10uF tantalum cap in the output will help with "noise"
What is the code on the chips in your modules?