Connectivity graph display is too small

I cannot magnify the image to see the name of channels. How can I use a magnifier or see it larger. As I scroll it only expand the middle of the image and I cannot see the top.

Unfortunately, this is not possible. This graph viewer suffers from many limitations and is currently being rewritten by a group of students. Not sure what's the timeline, but we might need a few extra months. @MartinC

One solution is to evaluate the connectivity over less sensors at once.
And you can always represent the connectivity graph as an image, in which you can zoom, click on the connections to see the actual values... That display is not as good looking, but actually more readable and more exhaustive.

How can I find my region of interest or check which channel is related to which region?

For the CTF systems, the name of the MEG channels indicate where the are.
For the other systems, you need to refer to a spatial display of the MEG sensors.

You can't related a sensor to a brain region, if this is what you are asking for. Look at the typical topography for a very focal MEG response, the highest field values are recorded away from the location source. One sensor can be involved in recordings the response of brain regions that are not that close.

I am using the Brainstorm version of Jan 2020, if I update it, will I lose my data?

If you set up Brainstorm as indicated in the introduction tutorials (no data in the brainstorm3 folder), you will not lose anything by updating the software. Updating is recommended every month.
https://neuroimage.usc.edu/brainstorm/Tutorials/CreateProtocol#Brainstorm_folders