Your understanding in that phrase is lacking. So if you practice your understanding up more level, nothing is necessary to change or to request, because you can notice the explanation by yourself, after you recite nd recite the briefed phrase.
Many phrases in tipitaka, abhidhamma, and commentary were taught in brief for easily memorizing of the practitioner, because in ancient theravāda tradition we orally memorize our kammaṭṭhāna-phrase before we meditate follow it.
So, what you want to do, the explanation of the brief phrase, is what the practitioners generally do in every meditation types. We do it until the meditation will be level up.
Also, this is the reason that why we already have the abhidhamma and ancient commentary in buddha time, too. Because in buddha period, there has not just the educated people who can enlighten at the fist time ever they listened dhamma. But there also has too many uneducated people who cannot understand and cannot enlighten, too. So they need the very deep explanation, which sāriputta had to answer to them because the buddha promoted him as the teacher of enlightenment in AN ekakanipāta ekapuggalapāli, such as appeared in M.N. mūlapaṇṇāsaka mahāgosiṇgasālasutta which every etadagga go to sāriputta's home to listen the very deep dhamma (the explanation) from him.
So, what you need will appear after you recite and recite the memorized ancient phrase again and again (parikamma).
For the example: when you secondly recite "May I be safe", the "your trying-to-safe-your-self effort" will little by little appear to you, such as when you try the vegan food to avoid ass injure by a hard shit, the secondly recited word will appear to you "this is what I recited 'May I be safe', this is giving happiness to my self, then I should do this giving to the other to meditate mettā", etc.
"Mettā to practitioner self" is just a preparation, it is not meditation.
In the path of purification, loving kindness meditation section, wrote:
when the practitioner doesn't know how to mettā, he should mettā to himself, before meditate mettā follow the tipitaka. "May I be happy, free from suffering hatred, difficulties, and troubles, and may I live in happiness!"
It is because the uneducated practitiner can easily notice giving-happiness-to-himself mind by this way. When he know what is mettā, then he can let the giving-happiness-to-the-others mind arise.
Read pāli cannon in pāli language is better, I recommend.