Issue Resolved Every Deck is showing 20 Cards
I will share screen shots explaining how to resolve this issue that your every Anki deck is showing 20 cards. Actually its default setting to read 20 cards from each deck to memorize the cards. Well you can change it and view all cards by increasing it according to your own setting. I would say increase it to 1000.
Step 1 and 2
Click on setting button of any deck it will change the setting of every deck.
Then Click on Options.