Arrow Key Malfunction in Excel

Since laptop keyboards are not standard (and may even differ from one model to another, even within the same brand), you need to indicate the exact model of your HP.

But first, take a good look at your QWERTY keyboard again: if you see a key marked "Scroll Lock," that’s it; and you may need to press a < Fn > key to disable or enable this function.

Reminder: disabled (corresponding LED off) => the cursor moves from one cell to another; enabled (LED on) => the sheet moves in the direction of the arrow keys.

My HP 260 G3 PC

I couldn't find a picture of the QWERTY keyboard of
your HP 260 G3; but I read that on some HP laptops:

< Fn >< left arrow > = < Scroll Lock >
< Fn >< right arrow > = < Pause >

Maybe that's applicable to your laptop?

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I also read that some laptops have no < Scroll Lock > key,
nor any key combination to simulate it; in that case, it seems
that the only solution is to display the on-screen keyboard: then click on
the < Scroll Lock > or < Pause Break > key.

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Check your HP 260 G3 manual, in the Keyboard chapter; if there is
a < Scroll Lock > key or a way to simulate it, it should be indicated there.

Besides that, I can't help you further: no other ideas.