Bismillahir Rahmanir Rahim.
Assalamu 'alaikum wa rahmatullahi wa barakatuh.
To change colour from colour to black and white or from black and white to colour , follow the step by step guide below.
Tap anywhere on screen to show the bottom menu and tap the Settings option
Tap the indicated icon to change colour to black and white.
Wait for a second for the colour of the page to change.