In PowerApps: How can I go with the nextArrowIcon that is outside the gallery to the next record from my gallery with the Id++ for example clicking the next arrow or back arrow should select the next record if currentrecord is with Id1 it should select id2 and then id3 and backArrow should select the previous Id? Everything is stored in 1 Table.

And we prefer not to make collections if possible but directy use Dataverse instead. With collections we can create a variable Index and then filter the Collections.