Lina Goldberg's 'Move to Cambodia' website usually has a pretty thorough and up-to-date summary of the visa situation:
https://www.movetocambodia.com/planning-your-move-to-cambodia/cambodia-visas/
However, since the new visa extension types were introduced about 18 months ago, there has been a lot more uncertainty and variability - different requirements and objections may sometimes be raised, depending on which agent you're using, or which office you're applying at, or which side of bed the processing officer got out on that morning. These are usually annoying rather than disastrous setbacks, though; you can apply probably apply again somewhere else a few days later and get a positive result.
The 'searching for employment' extension is called the 'EG' type, and is usually the easiest to get. But in theory you can only get one (though some people have apparently been lucky enough to get one or two further extensions on one), for a maximum of six months, and - I think - only single entry; so, of rather limited usefulness! And some people have had problems getting one if they've been in the country for an extended period before (but I think only quite long periods, and up to fairly recently; one lengthy visit a few years ago shouldn't be an issue).
If you're over 55, the easiest thing to do is get the 'ER' visa for retired people. In theory, you're supposed to be able to prove that you are over retirement age in your home country, are not working, and have sufficient funds (no guidelines stated on how much this is!) in Cambodia to support yourself; but in practice, at the moment, if you're 55 or over, no questions seem to be asked at all.
Good luck!