Changing default apps
Pick the default app you wish to change, for example, for your bowser you can pick one of these, or for swapping Google apps, Simple Mobile Tools
Changing apps on newer androids
Install your replacement app.
You will be asked if you want to make it your default. Yes.
In the next window, tap to select it and tap to make default.
On older androids
Install your replacement app.
Go to Settings -> Apps.
On the Apps screen, tap the three-dot menu on the top right.
In the menu that appears, tap Default Apps. A handful of default apps appears.
Tap the default app you wish to replace. Android will display a list of the apps you have installed on your device.
Tap the app you want to use as the default.