I usually have problems with the light-squared bishop when Black takes it out of the pawn chain and doesn't exchange it, but instead either protects it with the e-pawn:
rn1qkb1r/ppp2ppp/4pn2/3p1b2/3P1B2/3BP3/PPP2PPP/RN1QK1NR w KQkq - 0 5 1. d4 d5 2. Bf4 Bf5 3. e3 Nf6 4. Bd3 e6
or moves it back to g6:
rn1qkb1r/ppp1pppp/5nb1/3p4/3P1B2/3BP3/PPP2PPP/RN1QK1NR w KQkq - 3 5 1. d4 d5 2. Bf4 Bf5 3. e3 Nf6 4. Bd3 Bg6
If I exchange bishops, then Black will have either a very strong control of e4 to place a knight (when protected by the e-pawn), or a semi-open file for the h-rook (when in g6). If I don't exchange it, then the constant threat of Bxd3 hinders my development; I can't play the usual London moves c3, Nbd2 and my queen has to keep an eye on protecting the bishop.
In all videos about the London that I've seen, it's assumed that Black will keep his light-squared behind the pawn chain or will exchange it in d3. How do you deal with it when in those other cases?