why doesn't my samsung galaxy tab 3 (8") remember my wifi password?

[AC Question]

after shutting the tablet off, I have to re-enter the password. I've had the tab for about a year, but the problem only started 2 days ago. Just prior to this problem, I turned the tablet on, but the screen just went blank (with a slight black glow). I had to push and hold the power button to get the tablet to boot. When it did boot, that is when the password problem first started.