Q:

Font Changes on different android versions

i've used sp instead of dp for textsize on a textview,my device(7 inch) android version is 4.1.1 but it's Font changes and got larger on a device with same inch but Android 3.2.how can i prevent this.

A:

Independently from Screen size, different devices can have different screen resolutions, which gives different screen densities. As such you should always work in device independent pixels, so your best bet is to switch from SP to DP for your font sizes. Each device will handle SP differently. 
The system will automatically scale based it's resolution.
More about pixel density and screen resolutions on Android and what it means for the developer found here.
Edit: (from comments below)
You can add your own font the the project by placing it in your assets folder and calling 
Typeface tf = Typeface.createFromAsset(getContext().getAssets(), "myFont.ttf"); 
followed by 
TextView.setTypeface(tf ,1); 

