title: Upgrade default Python 3.5.3 to Python 3.7.2 on Raspberry Pi 3 Stretch
body: <p>I want to upgrade the default Python3 which is Python 3.5.3 to Python 3.7.2. When googled I found many sites telling how to install latest python 3.5 and other versions including python 3.7.0 but none of these sites were telling how to upgrade from python 3.5.3 to python 3.7.2. So I tried to install Python 3.7.2 instead of upgrading the default Python 3.5.3. After some searches I got a guide on How to install Python 3.7 on Raspberry Pi. Here is the link to the website: <a href="https://www.ramoonus.nl/2018/06/30/installing-python-3-7-on-raspberry-pi/" rel="nofollow noreferrer">https://www.ramoonus.nl/2018/06/30/installing-python-3-7-on-raspberry-pi/</a> . So I followed the steps and successfully installed Python 3.7.0 on my Raspberry Pi 3 and set the alias of python and python3 to python3.7.0 and now when I enter <code>python --version</code> or <code>python3 --version</code> it gives me 3.7.0. But now I have another problem that is when I shutdown or reboot my Pi and switches it back on and I type <code>python --version</code> it gives me 2.7.13 and  <code>python3</code> it gives me 3.5.3. So please help me with this matter.</p>