of course you can set up password for guest network. There are password settings right under the guest network menu. You can also disallow the guest to access your LAN. In addition, you can even set up a separate account for accessing the USB storage.

Check the emulator and you will see what you need
www.tp-link.com/resources/simulator/ArcherC7_3.0/Index.htm

Thanks Tobaco. I was able to setup the Password for my Guest Network. However, before I was able to test the Guest Network I took the opportunity to upgrade the firmware at the same time.

After the firmware upgrade the router lost all settings. Wireless devices had no connection to it. The network names of the 2.4 and 5Ghz changed to TPG defaults. So I logged back in to perform a configuration Restore. The Restore apparently was successful. I was able to get the correct network names broadcasted and all wireless devices worked fine.
However, the Guest Network would not work. It would accept the password I created earlier before the firmware upgrade and said connected but would not connect to internet. I tried to login to the router to see what else I could do on the Guest Network but it would not accept my User Name and Password! Not even the factory default admin, admin.

Please help!

After firmware upgrade, did you reconfigure it manually or use the configuration file to make it work?
If the latter, you have to reset the device to factory default and reconfigure it step by step.
You didm't mention hardware version of your C7, but is it V2? Did you read notes in firmware download page?
http://www.tp-link.com/en/support/download/?model=Archer+C7&version=V2#tbl_j

It's Hardware Version 2.0 which I have chosen the Firmware correctly. I restored the configuration file which I backuped just before the firmware update. One would think this should worked but it did not! I could do a reset to factory default and reconfigure it step by step. I guess this is the only choice to do it. I shall report back after that to tell if the Guest Network etc work. Thanks.

Thanks Vivian and others. I performed a factory reset & configured it manually. Although I went through some hiccups but I had everythings like Guest Network logon, changed original IP from 192.168.0.1 to 192.168.1.2 etc. working. IP 192.168.1.1 is reserved for the Netcomm modem. I also have WD MyCloud and MyBookLive NAS drives each connected to AC1750 Router and the Netcomm modem. After 3 weeks of messing with all the operational issues now it only left the WD MyCloud Safepoint backup problem to deal with. Sincerely thank you again.