If, what IF. First of all you entered Thailand using this visa on 4th of July. At entry the Immigration Officer stamped your visa "Used" and put a new stamp with the text, arrival date
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/21 and Admitted until, I guess
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/21.
You need to visit the Immigration Office before the Admitted until date and apply for a 1 year Extension of Stay, that 1 year will start on the Admitted until date, not the day you took a plane towards Thailand.
If the Extension of Stay is stamped in your passport, you directly apply for a Re-Entry Permit, cost 1.000 thb. If you visit Europe and come back before the new permitted up to date, guess
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/2022 you use the re-entry permit to enter Thailand. If you come back after that date you need to apply for a new Non Immigrant B visa before you make your way to Thailand.