How do i jailbreak an iPhone 4 so it can download older versions of apps

Doggo
04.11.2017

Ducky
04.11.2017

That would depend on what version of iOS it is running.

If it is running the latest compatible version (iOS 7.1.2) then you can use Pangu to jailbreak it - http://en.7.pangu.io

For the apps, you'd want to install AppCake. Usually it would be AppAdmin but it only supports iOS 8+

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