The two search tabs serve different purposes. Neither tab changes a saved card's value just because you open it.
Cards
The Cards tab searches the card catalog. Use it to find the correct player, year, set, number, insert, and version before adding a card.
Catalog coverage varies. A missing result does not prove that the card does not exist, and a nearby match should not be treated as exact.
Comps
The Comps tab shows reported sales for a selected catalog card and grade. Choose the correct card and grade, then use the available date and price filters to review the rows.
A sale price is different from a current asking price. To inspect asking prices for an owned card, open Active Listings on its detail page.
Saved collection values
Research results can include other versions or grades. Your saved copy uses its own confirmed identity and grade. See How Cubbby card values work for how its estimate is selected.