Change selected row background color in StyledTableItemDelegate

[Serg96]

Can't change background color of a selected row. Selection is always in default ubuntu style. How can I change this?
Here is my function paint. As you can see, I try to set the background using this: viewOption.backgroundBrush = QBrush(QColor("#000000"));
@void StyledTableItemDelegate::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
QPalette pal = option.palette;
QStyleOptionViewItem viewOption(option);

if (option.showDecorationSelected && (option.state & QStyle::State_Selected)) {
    viewOption.backgroundBrush = QBrush(QColor("#000000"));
}

viewOption.palette.setColor(QPalette::Text, "#6bc74c");
viewOption.font = QFont("arial", 10);
if(index.column() == 1) {
    viewOption.displayAlignment = Qt::AlignLeft;
}
else if (index.column() == 2) {
    viewOption.displayAlignment = Qt::AlignRight;
}

QStyledItemDelegate::paint(painter, viewOption, index);

}@