All your advertisements should appear under your user profile. They also should appear in the public searches where each result list is sorted differently. Your selling bitcoins online advertisements are sorted by a combination of several different factors. Price plays an important role, but also the popularity of your payment method and your reputation. We may limit the number of visible advertisements in the result listing so that we do not show advertisements from the same user. In this case the limitation happens by the price and the payment method. Your buying bitcoins online advertisements are sorted by volume, user reputation and price. The trade conducted by the advertiser and the trade conducted through a specific ad are weighted here. Local buy and sell advertisements are sorted by distance. The top six spots on the front page are filtered to include the most popular payment methods depending on the country.
If your advertisement does not appear to logged out users, the reason is probably that you have first time buyer limits or minimum required trade volume limits set. Since not logged in users have virtually no reputation and prior trades, they cannot see advertisements with these kinds of limits. Also if you do not have enough reputation yourself for your own advertisement, you may not see your advertisement in the listing.
For ONLINE_SELL advertisement you need to have minimum of 0.4 BTC in your LocalBitcoins wallet to have your advertisements running. You can still sell smaller amounts with advertisement limits. This is spam protection measurement.