"My mom was with me while I was doing "Malcolm" and stuff, she'll bring up things or trips we went on or big events that you would think I'd remember -and it's a new story to me", he said. "But we were talking about Malcolm [in the Middle] and how it started, and I don't really have memories of being on the show".
"I love to be able to look back", he said of the journal.
In a previous episode of the competition, Muniz revealed that he broke his back in a vehicle crash in 2009 while auto racing.
Muniz's "Malcolm in the Middle" co-star Bryan Cranston told "DWTS" cameras, "I will tell him, "Remember this?"
Detailing what happens to his body during one of his episodes, he said: "First, I lose my peripheral vision and I can see people but I can't recognise them".
A chance of rain to start your work week
It looks like the dry period will be brief as we track additional rain chances back into the forecast Tuesday and Wednesday . On Monday skies will remain mainly cloudy with some scattered showers possible, an isolated storm can't be ruled out.
"Despite his memory loss, Frankie is "happy" with the acting career he's had, which also saw him appear in "Arrested Development", "Dr Dolittle 2", and "Lizzie McGuire".
Muniz, who suffered a serious vehicle crash in 2009 while competing as a professional race-car driver, has also endured several concussions - but he says his health battle doesn't affect his desire to work in Hollywood "at all". "I just don't necessarily remember".
The former child star returned to the spotlight earlier this year after accepting a spot on the dancing competition show, Dancing With the Stars. "I didn't really take them in". "Every time I go to the doctors, they tell me I'm just insane", he laughed. Recently, Muniz admitted that he doesn't remember starring in the sitcom though, or most of his life before now. "Even if I don't remember, I'm happy".
Frankie and Witney received a score of 24 out of 30 points, an improvement on their 21 from last week.