Do you mean board name or usb device name?

You might have to change that in Device Manager if that is possible. Visual Micro reads the WMI database to discover device names.

However it does also attempt to match the VID/PID with board.txt so you are right to consider that.

You have not said which hardware you have or what cores you have installed so you have two options

1) if you are using arduino with AVR and have not used board manager then the boards.txt will be in arduinoide\hardware\arduino\avr\...

2) If you have used board manager then open the visual micro explore, click the Board Manager tab then hover the mouse over your hardware. The location of the boards.txt will be shown as links in the info panel at the bottom of the explorer.

If you make changes to boards.txt then click Rescan or restart the ide.

You can copy boards in boards.txt or you can add your own boards.txt to the arduino sketchbook\hardware folder

For example I created a copy of the Uno board to a boards.txt that I created in :-myDocuments\Arduino\Hardware\MyBoards\avr\boards.txt


The definition is the same as the original with 3 minor changes. You probably only need the first two if sparkfun uses the arduino core from the ide.

1) Renamed the BoardID. to myuno.
2) Renamed the board name from "Arduino/Genuino Uno" to "Test Uno"
3) Changed core=arduino to core=arduino:arduino

myuno.name=Test Uno

myuno.vid.0=0x2341
myuno.pid.0=0x0043
myuno.vid.1=0x2341
myuno.pid.1=0x0001
myuno.vid.2=0x2A03
myuno.pid.2=0x0043
myuno.vid.3=0x2341
myuno.pid.3=0x0243

myuno.upload.tool=avrdude
myuno.upload.protocol=arduino
myuno.upload.maximum_size=32256
myuno.upload.maximum_data_size=2048
myuno.upload.speed=115200

myuno.bootloader.tool=avrdude
myuno.bootloader.low_fuses=0xFF
myuno.bootloader.high_fuses=0xDE
myuno.bootloader.extended_fuses=0xFD
myuno.bootloader.unlock_bits=0x3F
myuno.bootloader.lock_bits=0x0F
myuno.bootloader.file=optiboot/optiboot_atmega328.hex

myuno.build.mcu=atmega328p
myuno.build.f_cpu=16000000L
myuno.build.board=AVR_UNO
myuno.build.core=arduino:arduino
myuno.build.variant=standard
 

If you add a board to a new empty boards.txt in the location as I described that will be merged automatically into your boards list in visual micro and the arduino ide.

You do not need to copy an entire boards.txt, just clone a single board.

So you will find the sparkfun boards.txt and I think the architecture of your board is avr but when you see the boards.txt you will see the folder names which tell you the architecture.

When you find the sparkfun boards.txt just grab your board from it and rename as described into a new boards.txt

hope this makes sense?

Sorry typo in my path example

In the Arduino world your Arduino Sketch Book folder is usually "MyDocuments\Arduino"

The sketchbook folder is the folder that appears when you click "File>Open>Arduino Project".

Then below that folder you can can create a "\Libraries" folder and a "\Hardware" folder

Therefore the correct path is:-

MyDocuments\Arduino\Hardware\MyBoards\avr

okay two possible solutions

change

jypromicro.build.variant=promicro

to 

jypromicro.build.variant=sparkfun:promicro

NOTE the sparkfun: has to match the name of the package folder above the original boards.txt. My example assumes it is called sparkfun but it's probably something else

OR

Option 2: Find the original boards.txt folder and you will see the \variants sub folder. copy the folder to below your boards.txt keeping the same structure as the original.

For option2 you would not add the sparkfun: prefix to jypromicro.build.variant

Great well done.

Your next question is a little out of my domain and often differs depending on board.

You also need to be careful if you manage to change the device name or id then be sure the sparkfun tool chain will work okay with it.

Notice that in my earlier Uno example there are a variety of VID/PID combinations.

The VID/PID is used to establish the board in Visual Micro

myuno.vid.0=0x2341
myuno.pid.0=0x0043
myuno.vid.1=0x2341
myuno.pid.1=0x0001
myuno.vid.2=0x2A03
myuno.pid.2=0x0043
myuno.vid.3=0x2341
myuno.pid.3=0x0243

Some board defs also state a build.usb_product="SimpleMidiUSB" which is worth reading about to see if that can be used to change things.

Device Manager is a registry/wmi system which you could probably hack.

Solved
variants folder name have to be the same as .build.variant name
in my case m5ow_esp32