Not enough memory(RAM) for just anything

I recently updated Photoshop because there's always an annoying pop-up trying to convince me to update the version every time I open the program. 
After the update, I used the software and tried to save the psd file into JPEG and there was an error message that said I could not save it because there was not enough RAM.
The same thing happened when I used just a brush or eraser. 
I did fix the memory usage capacity to max in preference and did the purge thing. None of those works.
I basically can't do anything with this software right now and I am paying a monthly subscription for not being able to use it.
Please fix or let me revert it back and never send a pop-up message trying to force me to update ever again if the update can only make things worse.