How can I be automatically directed to the Go SMS Pro app?

[AC Question]

go sms pro

I recently downloaded the GO SMS PRO on my ACER phone, but everytime I open my messaging it shows two options, the go sms pro bar on the upper portion and regular messaging tread. I tried checking my settings and enabled go sms pro but still showing the same thing. I wonder how I can automatically be directed to go sms pro app?

thanks!