Just follow the instruction very carefully
Open your whatsapp , app click on settings( which is present on three dot on the right hand side upper most corner) , then click in the following order
Settings > Account > Privacy > Read receipts (it is last option) tick it according to your priority.
if you want blue tick let it be clicked , and if you don’t want to blue tick then unclicked it. but after disable it all the person who will sent a message to you, they will not see blue tick even after your reading and vice versa.
Now you have done your task…
If it is clicked/ticked then there will be blue tick for seen message & if it is not ticked/unclicked, there will be only two tick but not blue.