Your Chat history can be downloaded in a CSV file. But in some case, if your text contains some of special characters, it may occur font errors.
Of course, you want to make it appear in valid font so that you can read. And here is how:
Step 1: Import Data
Step 2: Choose your History file to Import
Step 3: Choose Delimited and Unicode (UTF-8)
Step 4: Choose Comma
Step 5: Choose position to place the new file
It's done now :)