Open Edit PDF text and choose your PDF. The editor opens with big coloured buttons at the top: Edit text, Add text, Picture, Sign, Highlight, Erase, Draw, Shapes, More.
Need more tools (underline, stamp, forms, find and replace…)? Tap More. Tap Simple mode to come back to the easy view.
Open More, tap Show Panel, then the Find & Replace tab. Type the word in Find, the new word in Replace with…, and tap Replace all.
When finished, tap ⬇ Download at the top to save the edited PDF.