Memtest is not like a hard drive test. It will run over and over again until you stop it by pressing the Escape key, as explained in the user guide on the website if you'd bothered to read it.
The developer of Memtest says that most errors should be flagged up within the first five passes, so there was no need to let it run all night. As soon as you see errors appearing, you're done. Stop memtest at that point and replace the RAM.
You have already run it long enough. 32 errors means the RAM needs replacing. If you have more than one RAM module installed & you want to know which modules need replacing, test each module separately.