Lock Screen Apps/Stock Messaging App

[NastyNeil]

Is there a way I can change the stock messaging app to GoSMS? I can not for the life of me figure it out. I like the stock messaging app a lot, but I am on Sprint, and for some reason outgoing MMS is smaller than it should be. Has anyone else been able to A) change lock screen apps or B) figured out a way to send out MMS in a bigger size without rooting? GoSMS will let me, but I would rather stay with stock. Also, has anyone else notice that screen grabs come out distorted when sent out. GoSMS helps this issue as well, but again, I would rather use the stock messaging.

Thank you in advance.

 

[NastyNeil]

Well I searched forum, instead of being lazy, and found out how to switch the messaging app from the lock screen, but if anyone has any info on the actual stock messaging app itself, when it comes to MMS and such, it would be greatly appreciated.