SOLUTION:
ui->tableView->model()->setHeaderData(2,Qt::Horizontal,QFont("Arial",10,QFont::Bold),Qt::FontRole);
Actually everything is stated in the Qt Help, - just need to know how to correctly use it :)
@MXXIV said:
So QString::asprintf known in Qt4 was removed in Qt5.
It's QString::sprintf() that was in Qt 4 but removed in Qt 5.
Qt 5.5 introduced QString::asprintf() (and QString::vasprintf()), in fact: http://code.woboq.org/qt5/qtbase/src/corelib/tools/qstring.cpp.html#_ZN7QString8asprintfEPKcz (Hmm... there seems to be a documentation bug, and these functions aren't showing up. However, they are there for you to use)
