Tina Knowles Says Beyoncé Was 'Shy and Got Bullied' Growing Up: 'Couldn't Have Been More Proud of Her'

Tina Knowles is taking a trip down memory lane.

Sharing a video of her interview with Vogue on her Instagram page on May 26, Knowles, 70, opened up about her favorite memories of her children when they were young and called Beyoncé, Solange and Kelly Rowland her "three girls."

“Beyoncé, she was very shy and she got bullied a bit but the day that she stood up for someone — she didn’t stand up for herself she stood up for them," Knowles recalled. “I’m getting emotional talking about it. I was just, I couldn't have been more proud of her.”

Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from juicy celebrity news to compelling human interest stories.

Knowles, who shares Beyoncé, 42, and Solange, 37, with her ex-husband Mathew Knowles, then went on to share her favorite childhood memory of her second daughter.

“Solange, was her signing a petition in school, she was only in like fifth grade and she was out getting petitions signed,” Knowles said. “So she’s always been an activist.”

Knowles often refers to Rowland, 43, as her third daughter and earlier this month she recalled on Today with Hoda & Jenna how Rowland came to live with the family at the age of 11. "That's my baby," she added.

Rowland's mother Doris Rowland Garrison died in December 2014 at the age of 66.

“Kelly was always this kid that just tried to protect everybody,” Knowles continued. “I have a memory of her with her best friend Barbara and her being a mediator and just being this little peacemaker.”

“Each child is different! But all so special. I believe kids are born with their personalities. My three girls All handled things very differently,” the fashion designer wrote in the caption of the video. “Learn their personalities and respect the individuality. Never compare the negatives , always praise the positive differences and pay attention to the things that you can brag on about them. They love it and it encourages positive behavior . Interview with Vogue.com At Vogue offices ❤️.”

Knowles' comments come after she revealed what Beyoncé and Solange's kids call her during an appearance on Today with Hoda & Jenna earlier this month.

The PEOPLE Puzzler crossword is here! How quickly can you solve it? Play now!

"They call me 'Grandma,'" said Knowles.

"It’s the best. With grandkids you don’t have the pressure of taking responsibility for how they get to turn out, so you get to just indulge them and let them have noisy toys that drive their parents crazy," she joked. "It’s just the best. They are the best. My grandkids are all super creative and I just love them to death."

While Beyoncé shares daughter Blue Ivy, 12, and twins Rumi and Sir, 6, with husband JAY-Z, Solange is mom to 19-year-old son Daniel 'Juelz' Smith Jr. with her ex-husband Daniel Smith.