The Red Devils have altered their formation to the 3-5-2 system for the campaign, which has seen them struggle immensely at the back in their Premier League matches.
The 63-year-old fears that he may have given his players too much to process in too short a time after arriving at the club in July.
"We give [the players] a lot of information and you have to work out that information," Van Gaal told reporters.
"There shall be a moment in the season that this information is not too much. At this moment maybe it is too much for the players.
"It's very difficult because we are starting with a new team and a new relationship between players so that's why it needs time."
United face West Ham United in their Premier League clash later today.