I have tried with the option align to object but nothing..

Other question:
why sometimes it's so hard to select some faces..it seems it's a problem of normal, but i have tried with the reverse node to fix them but nothing..

why sometimes it's so hard to select some faces..

are you sure you are in Selection State ? .. because some tools ( when in active state ) make the geometry look like the geometry is ready for selection .

at least this appeared to be the case in some occasions for me.
once in Selection State, i never had problems with selections.


.cheers

To the second question:

Probably you have hit the ‘b’ key which changes ‘select all’ to ‘select backfacing’ etc.