You can do this using the filter option in Card set.
Step 1) Go to Flashcards Buddy main screen > MENU > Setting > Markers
Step 2) Make sure you check on "Enable markers for card" Checkbox.
Step 3) Press on Markers setting right below and go to "Icons" setting screen.
Step 4) Define two marker icons like the one in screen shot.
First one with "Unlearned", Gray star
Second one with "Learned", Yellow star
Step 5) Save the setting and go back to the main screen.
Now, the marker icons are ready, it's time to set the filter in Card set.
Step 6) In Flashcards Buddy main screen, go to any card set by press on the card set item in the list.
Step 7) In "Card set" screen, there's "Option" button in right side. press the button and go to "Card list setting" screen.
Step 8) Scroll down to "Section 3. Filter cards by..."
Step 9) Select "Markers" radio button. Then select only "Unlearned" icon.
In this way, you can automatically filter out all the yellow star (learned card) from the card list.
Now, your card set is ready. It has filter option for the "Unlearned" item and all the learned cards will not displayed.
Step 10) Now, browse the card and press the star marker icons in top-left corner.
You will see the icon toggles between gray and yellow.
Step 11) If you feel like you have learned a card, switch the star to yellow (learned).
Then, card set list screen will automatically filter out the card from next time.