Yes, a Single Entry visa means you can use this once, on entry the visa get the stamp used and becomes invalid. You get a maximum stay of 60 days and you can leave anyday during those 60 days.
On return you might want to use the 30 day Visa Exempt Entry or buy a new tourist visa at the Thai consulate before travel.
Alternative is the 6 months valid Multiple Entry Tourist Visa, which will give 60 days of stay on each entry during the 6 months validity of the visa.
TM30 Notification of the address where the foreigner is staying
TM47 Notification that a foreinger is 90 days inside Thailand.
Two different things with two different computer systems to report, two different things to report depending on change address or the time you spent inside the Kingdom.
Welcome in the club, somehow some people think that discussion is not allowed, advice should be only what they want to hear and Immigration should adjust the law in Thailand on demands on the fist of a few idiots.
It is a shame such people do walk around without a leash and are free to use Social Media.
Take care, they are only though bullies using a keyboard/
As you have to show the tickets and the reasons of multiple visits, you can use the invitation letter for the same periods of time spending in Thailand.