Well, it is quite confusing, but think of it like this... First, let's say that we are not sure whether it's ei mănâncă or ei mănânc, so you'll say in your head, Eu mănânc (I eat), Tu mănânce (You eat) El/Ea mănânce (He/She Eat) Noi măncâm (We eat) Voi măncați (You (plural) eat) Ei/ele mănâncă (They/He/She (Plural) Eat)
Sorry, if I got a few words wrong but that's how I do it, I do that with all the words. It can help to use google translate sometimes too. My Dad is from Romania so he's been teaching me Romanian ever since I could talk. My main language is English so I am not fluent in Romanian yet.
Also, I found this in another comment that reply's to a questiona bit like yours.
you start doing it naturally once you progress. I will only explain present tense, as other tenses in Romanian are formed easy enough and you will master them if you know the present tense well.
The most important thing we should know about a verb to find out how it's conjugated is its infinitive form. In Romanian that is "a [infinitive]". For example: "a putea" (to be able to), "a vorbi" (to speak), "a vrea" (to want).
There are 4 types of verb groups in Romanian and they are distinguished by the ending of the infinitive form:
Type 1 - ends in just "-a". Examples: "a înota" (to swim), "a cânta" (to sing)
Type 2 - ends in "-ea". Examples: "a putea" (to be able to), "a vedea" (to see)
Type 3 - ends in "-e". Examples: "a merge" (to go/walk), "a plânge" (to cry)
Type 4 - ends in "i" or "î". Examples: "a găsi" (to find), "a urî" (to hate)
Okay! That's simple enough. Now, there are different conjugations for each group, but there are some subgroups of conjugation. Let's explore those:
For type 1:
We have two subgroups with different conjugation rules. Those are normal verbs and "-ez" verbs. For example:
We have "a înota" which for first-person singular is "eu înot" (I swim). That's a normal verb. However, we have verbs like "a picta" (to paint) which for first-person singular is "eu pictez" (I paint) and NOT "eu pict" as one might expect. Those are the only two subtypes in type 1 verbs and they have different conjugation rules. There is no easy way to identify which subtype it is by knowing just the infinitive, so you have to write down which one it is every time you learn a new verb.
For type 2:
Fortunately, there are no subtypes and there is just one type of conjugation for these verbs.
For type 3:
Just as for type 2 - just one type of conjugation.
For type 4:
Here we have some subtypes. We will break them down in two parts.
I. Verbs that end in "i".
Those are verbs like "a găsi"(to find), "a dormi" (to sleep). Just as in type 1 verbs, here we also have two ways to conjugate. Normal verbs and "-esc" verbs.
For "a dormi" the first-person singular is "eu dorm" (I sleep) - normal verb. For "a găsi", however, we have "eu găsesc"(I find) - so that's an "-esc" verb. Once again, there is no easy way to guess which one it's gonna be - so you have to remember that when learning the verb.
II. Verbs that end in "î"
Those are verbs like "a omorî" (to kill), "a urî" (to hate). Two conjugation types once again. Normal ones and "ăsc" verbs. As you can guess we simply have:
"a omorî"(to kill) - "eu omor" (I kill), but
"a urî" (to hate) - "eu urăsc" (I hate)
As you can guess - no easy way to guess which one it is gonna be, so just memorize for each verb.
Okay, that's all! Let's sum up!
Basically, considering all subtypes we have in total 8 different ways a verb can be conjugated. By knowing the infinitive you can narrow it down to one or two and then just memorize. But how does the actual conjugation work?
Basically, for each form you have to remove the suffix from the infinitive (that is, remove the "a" or "ea" or "e" or "i" or "î" at the end) and then add a different suffix depending on the situation.
Sorry, that was a very long reply from me, hope it helped though. :)