One of the main thing while setting up a VM is its size and cost. This article will help you to understand how to configure the VM size and the costs involved for the configurations.
If you have already created a VM then you can change the size from the management portal using the below option.
In the above case I have chosen the Size as D4_V2 which gives a 3.5GB Ram with 50GB HDD for a monthly bill of 119.78 USD. Similarly based on your production requirements you can choose to appropriate size.
Redeploy VM Image
This option can be used incase if you want to start from scratch. When you create a VM the Azure will keep the configurations you have chosen as a Template. This Template can be used for Redploying scenarios.
The Diagnostics information will allow you to understand the health of the VM. It will give critical information about the vital signs of the VM. You can configure the diagnostics as showed below.