Buttons Options (Colour,size) On Product Page


I am wondering how to change Products options to select :

how do I do to change it to >
'select an option' ?
instead of showing a colour or size option straight away ?

(in that case 'taupe' and '0-3 M' ) I feel it would make more sense to see 'select' and 'select'

i have attached a picture to make it more clear .

thank you very much

Do you use options or variations?