kiedis: i think there is a hard way and an easy way to do this type of thing. the hard way is doing what you have already tried, clearing away the original text, then typing in new text or even cloning the letters (i'd clone them on separate layers and then use guides to get them in place, that might work) - but all of that means heaps of work! the easy way is to find image generators that someone has put online for constructing this type of joke messages or greetings in. like this, for windows error messages:
error message generatoror this for windows crash screens:
windows blue screen generatorand here's a whole collection of sign generators of different kinds, some of them downloadable:
sign generatorsimage chef is another fun collection of generators.
that clipping came from this site:
fodey.com newspaper generator