Bismillahir Rahmanir Rahim.
Assalamu 'alaikum wa rahmatullahi wa barakatuh.
To keep the screen awake, follow these step by step guide below.
Step 1
Tap anywhere on screen to show the bottom menu and tap the Setting icon in the menu.
Step 2
Tap the Screen Awake option as indicated by arrow so that it has the tick sign.
Jazak Allah Khair