De'LonghiECAM293.52.B:Factory settinggrinding degree6.5

Hello,

I had already returned the KVA DeLonghi ECAM 356.77.S Dinamica because I changed the grind incorrectly and my coffee tasted very sour afterwards. Because of this experience, I am afraid to change the grind.
Since yesterday I have a new De'Longhi ECAM293.52.B with me. Unpacked and everything looked "new". I opened the coffee container lid and was very surprised: the new KVA has a grind level (factory setting) of 6.5 (grind level option from 1 (very fine) to 7 (very coarse))! Also unbelievable: although the grind level is set to very coarse, the coffee tastes relatively strong (a little too bitter) and the temperature factory setting is too hot (tongue burnt, although at level 2 = medium) and the coffee puck is dry, firm and round.
So everything indicates that the coffee beans are ground very finely.
Questions:
1. How can it be that the grind setting is 6.5 and not 4.5 (as usual)?
2. Why is the coffee so strong and the puck so firm at such a coarse setting (almost the coarsest!)?
Could it be that the Malgrad knob was inserted incorrectly during assembly in Romania?
Sorry, but I'm afraid to change the grind (see above).

I changed the temperature and aroma to the lowest setting (i.e. 1) (grind unchanged at 6.5): Now coffee tastes normal and drinkable (hot enough and with a bitter note but no longer too bitter). Incidentally, the crema was almost 1 cm with ECAM 356.77.S and only about 5 mm with ECAM293.52.B.

Should I send the KVA back? Is this 'new' KVA a return?

Thanks for your help
MfG Fidel