Copy and paste this code on you active theme’s functions.php file:

//#Create Qoutation
add_filter('wpcpq_create_quotation_label', function(){ 
return 'Your Desired Menu Label Here'; 
});

//#Quotation
add_filter('wpcpq_delivery_requests_label', function(){ 
return 'Your Desired Menu Label Here'; 
});

//#Pending Quotation
add_filter('wpc_pq_pending_quotation_label', function(){ 
return 'Your Desired Menu Label Here'; 
});

//#Pending For Approval
add_filter('wpc_pq_approved_label', function(){
 return 'Your Desired Menu Label Here';
});

//#Quotation Approved
add_filter('wpc_pq_pending_for_approval_label', function(){ 
return 'Your Desired Menu Label Here'; 
});