JEveAssets handles multiple characters on multiple accounts fine. Since it gets the data from API queries you have to setup API Keys for each account first (through CCP's account management page) and then configure the Key ID and Verification Code for each account before JEveAssets can query the keys.
The most basic way to change what JEveAssets shows you is with the "tools" menu which gives you a number of options to open different tabs that display the data in different ways. Most of that is pretty straightforward, just click the menu item and a tab opens.
Many (but not all) tabs have data cells arranged in rows and columns (the aforementioned Assets and Transactions tabs for example). In these tabs you can drag column headers and move them around to rearrange the order the columns are displayed in. You can double-click a column header to select it and then single click it to sort the data). You can also right click on any cell to open a menu containing a number of powerful features.
|Transactions tab with right-click menu open|
If for example you click on the highlighted Eve-Marketdata menu item shown in the screenshot above, it will automatically open your browser and look up the selected item (PLEX in the example above) on the Eve MarketData website.
Probably the most powerful feature is Filters. Filters are the key to unlocking the full power of JEveAssets. Without filters the Assets and Transactions tabs would be practically useless for any half serious Trader or Industrialist. There's just way too much data to find what you're looking for quickly (far less make much sense of it all) without filtering. But with filters, these tabs are extremely powerful.
For example here's an un-filtered Transactions tab.
The screenshot only contains the first few lines of the list but the full, unfiltered list has nearly 5,000 entries. So let's make it more readable by filtering the list to only show a single item 30 Day Pilot's License Extension (PLEX)
Under the Name column (the item name) right-click on 30 Day Pilot's License Extension (PLEX) to open a menu like in the screenshot below.
Then click on Contains to add a filter like in the next screenshot
When the filter is added the list automatically refreshes to only show PLEX like so
The filtered list contains just 129 lines (vs nearly 5,000 unfiltered) and makes it much easier to see how my PLEX sales have been doing lately.
You can use filters to sort by any data cell not just the item name, you can filter by date, price, owner (character name), region, station, etc., you can use different filter methods like "contains", "does not contain", "equals", etc., and you can even use multiple filters too.
For example to further reduce the PLEX list above you could use 2 filters to only show items that are named 30 Day Pilot's License Extension (PLEX) AND are in a particular region. Which in the example I've been using throughout this article lists just a single PLEX and looks like this
|Owner name removed to protect the innocent|
Hopefully this will help some of you unlock the full power of JEveAssets and get better use out of it!