Arduino UNO board does not sit flat on plastic base

Trying to screw the board to the base but the metal bits sticking from the power socket and the USB do not let the board to lay flat. It's up to the point that I cannot even put in the screw that should go next to the power socket.

Am I missing some step here?

Use plastic spacers or several plastic washers between the board and the base

I hade the same problem. So I started with the screw close to the power socket, It worked better. I also just screwed them on by hand so as to not break anything, everything felt so fragile.

Deseo comprar un kit de inicio con at mega 328p pero quiero preguntarles si existe una mejor alternativa, con algún otro procesador, que sea más útil a futuro y se pueda utilizar en más proyectos,
Que opinan ?