It could help if you also speak another language which has seperate singular and plural forms for "you"; if you only speak English, perhaps using the middle english thou (singular) and ye (plural) might be helpful in remembering; so:
Plural you = ye = sibh
Singular you = thou = tú
Unless "thee" and "thou" are already part of your English idiolect, and the difference between them is obvious to you (which isn't the case for most modern English speakers), then it doesn't make much sense to have to learn that difference in (archaic) English so that you can understand the difference in Irish.
English already has colloquial ways to differentiate between singular and plural "you". Some Americans use "y'all" (though some of them use it as a "polite singular you", much like "vous" in French, which can be singular), most American and European speakers of English recognize that "you guys" is a plural form of "you". Many English speakers in Ireland and Britain will recognize "ye" as a plural "you", but it apparently confuses some American speakers.
But it's not obvious to most modern English speakers that "thou" is singular - it's certainly not any more obviously singular than "you". So if Duolingo are going to adopt a "plural you", it should be "you guys" (unambiguously plural to the vast majority of English speakers, but unquestionably informal and unsuitable in a formal register), "ye" (confusing to a significant number of English speakers) or "y'all" (mainly used by Americans, some only as a plural "you", some as a "polite singular you", like "vous").
Off hand, I can't think of a single example of an exercise on Duolingo where "you guys" would be inappropriate in the translation of sibh, agaibh, oraibh, etc. But encouraging "thou" in the translation of tú or agat or ort to reinforce the singular/plural difference in "you" would be madness, IMO.
I also find pronunciation of words holding me back. Many Irish words cannot be read phonetically so if it just shows it without any way to know its sound that is a big disadvantage. Many of the other courses sound out each word. Thanks for the pronunciation help evin.lee.
Most Irish words can be read phonetically, if you follow the rules for Irish phonetics, just as you follow the rules for French phonetics when pronouncing "Paris" in French, etc.
Check out https://forum.duolingo.com/comment/30527560 for an explanation of why Irish doesn't have audio for every sentence, and watch the first link, Sounds and Spelling of Irish video by Karen Reshkin.
In the present tense, 1st person verbs can be combined with their pronouns (mé and muid) to give táim and táimid.
"You" is the 2nd person, and in Standard Irish, you don't combine the 2nd person pronouns with the verb in the present tense - you must use the "analytic" forms tá tú (one person) or tá sibh (more than one person). But there is an archaic form of the 2nd person verb táir, that someone requested be added as an acceptable alternative answer, and unfortunately that suggestion was accepted, and now Duolingo thinks that you actually meant to enter the obscure táir form but you made a typo, so that instead of giving you a useful correction, you get a confusing correction that refers to a obscure form that you won't find in any of your reference books.