Can I convert my Non IMM ED visa to Non ED Plus after arriving in Thailand?

Why Thailand for an upper university degree, terrible universities here, better to go UK or anywhere Europe. Or if about being poor, then get a “online degree”.

For CU case, the letter they provide to immigration requests non ED visa (ed plus is actually same as this already). So when you extend your visa, you get the privilege of ed plus (no more need for reentry permit). You have to clarify with immigration officer as well as they said it depends on the letter your school provided. If other students in your university got the same visa type and stamp ,it is also possible that the immigration officer missed to give the same stamp that says exempt from reentry permit. This happened to my friend and he came back to get it stamped again.

No...

The Ed Plus is a one year visa available to university students who have completed their degree study. That's why it's called Ed Plus.