Table formatting for IE and Firefox

Have you checked for mark-up or CSS errors? They often cause browser inconsistencies.

https://codex.www.ads-software.com/Validating_a_Website

I see that there at a lot of errors, but am unsure what to do about it – at this point my skills limit me to using templates and plugins

is it unusual for sites to have errors?

No, a website will normally have errors.

It’s not unusual, partly because not all errors are really problematic – some are caused by browser differences and changing coding standards. But I just looked at your site, and you do have some “bad” ones – the ones having to do with missing or extra or unclosed tags – tend to cause problems. Something is messed up in your header.php file – with the end head tag and body tags. And then in your table, you have incorrectly formatted lists. So start by tracking those down.

thanks, i will start digging into it

Is this something that might be solved by changing my websites theme? i am looking for an approach that does not involve directly altering code in any way (this only tends to get me into more trouble)

Try deactivating plugins to explore whether any plugins are responsible for errors.