Why don't the checks in Whatsap turn blue by all my contacts when read?

[Windows Central Question]

why dont the checks in whatsap turn blue by all my contacts when read?

by some of my contacts when they read my message the checks turn blue, but other contacts read my messages and the checks stay white, they dont turn blue. whats the cause for that?

 

[Ashish Gupta888]

Re: why dont the checks in whatsap turn blue by all my contacts when read?

They need to update WhatsApp to the latest version.