I am trying to get into deep learning. I installed Anaconda to use jupyter and generally not to care about installing all of those packages like matplotlib etc myself. But I
The most pain-free approach that worked for me was to install the legacy version of Anaconda. If you want Python 3.6 as default, I recommand downloading Anaconda 5.2.0 which was the last version to use Python 3.6 in base environment as default. (Legacy versions can be found here.)
If you also want the latest version of Anaconda, there is an easy way. With Anaconda 5.2.0 installed, you can actually update to newer versions of Anaconda by
conda update anaconda
which will try to update all your packages except keepping Python at 3.6.x.