Edit text on a slide image
A slide exported as an image has lost its text boxes. Select the wording, type the replacement, and it is redrawn in the deck’s own typeface on its own background, including gradients and brand colour.

What makes this one hard
Decks are built on brand colour and generous spacing, so a correction lands against a flat field with nothing to hide behind. There is no grain or texture to absorb a slightly wrong shade.
Why not just edit the deck?
Always edit the deck if you have it. This is for the case where you have a PNG or a screenshot of a slide and not the file, which is common when the deck came from someone else.
Does it keep the brand colour?
The background under the text is continued as it is, so a brand gradient or solid field stays exactly the colour it was.
One credit is one edit. Credits never expire.