Adding a word in present tense instead of past
I see @ericb100 already provided a good explanation here. :)
You should first understand that the "LingQ-way" is to count every form of a word as a separate word. If you just go with this, roam, roamed, roaming would all be different words to lingq and to "know". I think *most* folks who have used LingQ a long time would suggest you follow this approach. Otherwise you're really bucking the system. I think over time you'll see the "LingQ-way" really is the best approach for a number of reasons which I won't go into.
In any event you can deal with it a number of ways:
1. LingQ "roamed", but add or select a definition that also indicates the inifinitive form. So you might have the definition as "(roam) - <your definition in your native language>". Often others have done this already so you could just pick one of theirs
2. Most verbs get autotagged with the inifinitive form as one of the tags. You can just lingq the word and choose/provide a definition and the tag for "roam" may just be there. If it is, you can click on it and it will take you to reverso verb conjugation where you can see all the conjugations.
3. Mark a the word as Ignored if the word is not in its infinitive form. Some people do this.
Now that I think about it... It would be pretty cool to be able to put multiple words under the same umbrella definition right away (basically add more words/phrases for which your definition would apply).
It's a feature I've missed at few times and I had to find the word I was looking for somewhere in the text, often it being the same verb but in another form, before doing what I wanted to do, at which point I could've forgotten what I wanted to do in the first place.
Though being able to do that would go against LingQ's philosophy of focusing on the words you're encountering right at that moment and I can see many people go down a rabbit hole and being perfectionist about their definitions. I still wouldn't mind a more "remote" vocab manager though.