To use the LEFTB, RIGHTB, and MIDB functions in Excel to account for double-byte characters, use the following steps:

1. Type the formula into a chosen Excel cell.
2. Inserted the text argument as the first parameter.
3. Confirm the starting point argument is the appropriate number for the choice function.
4. Calculate the length of the characters to select for the choice function.
5. Verify the character result of the formula.