@Jim ********
First, let’s get savvy on all those wrong wordings:
*** when you enter on a single-entry 90 Days Non-Imm-O Visa, you will receive a 90-days stay permit.
The stamp in your passport says “admitted until” and a date in blue ink showing the expiry of this stay permit as being 90 days ahead of the day you enter.
The visa itself becomes invalid or “used”. Now you are in Thailand on a stay permit, not “on a visa”
*** for this 90-days stay permit you can buy a “re-entry permit”
A re-entry permit will allow you to exit and re-enter Thailand whilst keeping your 90 days stay permit alive.
ATTENTION: the re-entry permit only keeps your initial stay permit alive.
So, if you entered February 10th, you received an “admitted stay” until May 8th. The re-entry permit you buy for this stay permit expires on the same date – May 8th
***if you stay abroad after May 8th, you initial 90-days stay stay permit will expire, and you will need to restart from scratch